Re: English version for Mémento Python 3 (draft, readers needed)
On Wed, 2012-06-06 at 16:56 -0400, Jerry Hill wrote: For what it's worth, I've never seen either of those constructs (see overleaf and see over). Are they perhaps more common in a particular academic context, or possibly more common in places that use British English spellings rather than American English? Perhaps - overleaf is relatively common in documents here - while filling out forms, in exam papers, etc. However a quick search suggests the usage is in British and American dictionaries with the same meaning. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: English version for Mémento Python 3 (draft, readers needed)
On Wed, 2012-06-06 at 12:03 +0200, Ulrich Eckhardt wrote: block else for other cases - this sounds as if it was blocking the else. Maybe else-block for other cases, I would say else block. else-block is grammatically correct too, but I don't think I've seen it used regularly. RE: the order - else is being used as an adjective to clarify the noun block - in English the adjective comes before the noun (unlike a lot of European languages) e.g. we say the red book, not the book red, where the French would say livre rouge (I believe). If you want to put an adjective after the noun (for poetical reasons etc) then there needs to be another clause. e.g. the book, which was red but English hyphenation is complicated and I'm not sure. You're German and you say English hyphenation is complicated! ;-) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Open Source: you're doing it wrong - the Pyjamas hijack
On Tue, 2012-05-15 at 12:39 +0200, Pascal Chambon wrote: believe me all this fuss is pitiful compared to the real harm that was done numerous time to willing newcomers, on pyjs' old ML, when they weren't aware about the heavy dogmas lying around. A demo sample (I quote it each time the suvject arises, sorry for duplicates) | Please get this absolutely clear in your head: that | | you do not understand my reasoning is completely and utterly | | irrelevant. i understand *your* reasoning; i'm the one making the | | decisions, that's my role to understand the pros and cons. i make a | | decision: that's the end of it. | | You present reasoning to me: i weight it up, against the other | | reasoning, and i make a decision. you don't have to understand that | | decision, you do not have to like that decision, you do not have to | | accept that decision. | The above seems perfectly reasonable to me. You're working with Python anyway - a language organised by a team that gives full control to the BDFL... Imagine instead that you were talking about a bug in a proprietary piece of software (Oracle / Internet Explorer / etc) - do you think they'd let *you* make the decision, or keep the option under discussion until *you* fully understood the reasoning of the company that owned the code? No - they'd listen to your argument, weigh up the two sides, and make a decision on their own. The idea of having two sides able to make their cases and one person rule on them is incredibly common - it's how courts across the world work, and it's how management of any team (software related or not) goes. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Open Source: you're doing it wrong - the Pyjamas hijack
On Tue, 2012-05-08 at 15:20 +1000, Chris Angelico wrote: I hope that pyjamas can be restored at some point to a single live project. Whether that's headed by Luke Leighton or C Anthony Risinger (neither of whom I know at all and thus I can't speak to either's merits) or someone else, I don't particularly care I have met Luke (At Europython), and honestly it was his enthusiasm that got me to look at pyjamas in the first place. To be fair I still haven't used it in anger, but I've poked around a lot, it's been under consideration for several bits of work. Although I don't think I've met C Anthony Risinger, his behaviour has seriously put me off the project - and if I consider using it in the future I'm going to be pricing in the cost of maintaining a complete local fork as part of the decision. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: John Carmack glorifying functional programing in 3k words
On Wed, 2012-05-02 at 17:31 +0200, Tomasz Rola wrote: positive aura drives more people and more permamently towards you. Perhaps he should develop an alter ego that could stand side by side with Dalai Lama and see which one gets more attention. Really? http://www.google.com/trends/?q=bin+laden,dalai +lamactab=0geo=alldate=allsort=0 If all you want is attention then being nice doesn't seem to be the best option. (of course if you want any respect...) -- http://mail.python.org/mailman/listinfo/python-list
Re: Half-baked idea: list comprehensions with while
On Fri, 2012-04-27 at 19:57 +1000, Chris Angelico wrote: On Fri, Apr 27, 2012 at 7:49 PM, Miles Rout miles.r...@gmail.com wrote: We have if inside list comprehensions? I didn't know that, could you provide an example? You mean like: [x*2+1 for x in range(10) if x%3] Or like: print [ 0 if b%2==1 else 1 for b in range(10)] [1, 0, 1, 0, 1, 0, 1, 0, 1, 0] -- http://mail.python.org/mailman/listinfo/python-list
Re: Python Gotcha's?
On Thu, 2012-04-05 at 12:00 +, Steven D'Aprano wrote: The reason this is a Gotcha rather than a bug is because the JSON standard specifies the behaviour (probably in order to be compatible with Javascript). It's not to be compatible with javascript (you can use either in javascript) I believe the choice is to make the parser as simple as possible. Agreed it's a gotcha, but json is almost always generated automatically. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Python math is off by .000000000000045
On Sat, 2012-02-25 at 09:56 -0800, Tobiah wrote: For every floating point number there is a corresponding real number, but 0% of real numbers can be represented exactly by floating point numbers. It seems to me that there are a great many real numbers that can be represented exactly by floating point numbers. The number 1 is an example. I suppose that if you divide that count by the infinite count of all real numbers, you could argue that the result is 0%. It's not just an argument - it's mathematically correct. The same can be said for ints representing the natural numbers, or positive integers. However, ints can represent 100% of integers within a specific range, where floats can't represent all real numbers for any range (except for the empty set) - because there's an infinate number of real numbers within any non-trivial range. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: OT: Entitlements [was Re: Python usage numbers]
(Sorry for top-posting this bit, but I think it's required before the rest of my response) At the risk of wading into this from a UK citizen's perspective: You're imagining a public healthcare system as if it were private. Imagine you go to a doctor and say I've got the flu, can you give me antibiotics. In a Private healthcare system: * The doctor gets paid for retaining a client. * He is incentivised to do what you request. ... so he gives you the antibiotics. In a Public healthcare system: * The doctor is paid no matter what. * His job is to stop the population becoming ill. * By reducing illnesses he reduces his workload, without reducing his wage ... so he'll only give you antibiotics if he feels you are at serious risk, and giving you antibiotics carries less risk for the population than the risk of the population getting immunities. Same goes for surgery etc. On Mon, 2012-02-13 at 08:01 -0800, Rick Johnson wrote: And just how much healthcare dollars are you entitled to exactly? Can you put your entitlement into some form of monetary value? And how can we ever make a system like this fair? If someone works for 30 years and pays a 30% tax rate and another works for 2 years and pays 15%, then how do we delegate the fair share? If your children are educated privately then should you still be paying taxes for education? If you work for/bank with a company that doesn't need to be bailed out, then should you still pay tax for that? If you never need benefits (welfare) then should your taxes be paying for that? you can use that same argument for everything that taxes pay for - the only logical conclusion of that argument is anarchy (i.e. no taxes, and no government). If you are an anarchist then that's a different argument all together (not saying it doesn't have intellectual validity). snip Healthcare is expensive. Do you want a minimum wage doctor curing your ills? And the frivolous lawsuits are not bringing the costs down either. It's so expensive because of the marketing, and because of all the middle-men. A public health system doesn't need to do that marketing. They also don't need to put up with people who aren't seriously ill - I don't know how long your private appointments are, but here in the UK a standard doctor's appointment is 5-10 minutes. If they decide you're actually ill they may extend that. - bosses win, because they have reduced absenteeism, lower training costs to replace workers who die, and fewer epidemics that threaten their own families BS! With free healthcare, those who would have allowed their immune system fight off the flu, now take off from work, visit a local clinic, and get pumped full of antibiotics so they can create a new strain of antibiotic resistant flu virus! Thanks free healthcare! See my comments at the top. -- http://mail.python.org/mailman/listinfo/python-list
Re: replacing __dict__ with an OrderedDict
On Tue, 2012-01-10 at 09:05 -0500, Roy Smith wrote: I guess MongoDB is not a serious database? That's opening up a can of worms ;) ... anyway, cassandra is far better. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: How to support a non-standard encoding?
On Fri, 2012-01-06 at 10:03 +, Ivan wrote: Dear All I'm developing a python application for which I need to support a non-standard character encoding (specifically ISO 6937/2-1983, Addendum 1-1989). If your system version of iconv contains that encoding (mine does) then you could use a wrapped iconv library to avoid re-inventing the wheel. I've got a forked version of the iconv package from pypi available here: https://github.com/timwintle/iconv-python .. it should work on python2.5-2.7 Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: How to support a non-standard encoding?
On Fri, 2012-01-06 at 12:00 -0800, jmfauth wrote: The distibution of such a codec may be a problem. There is a register_codec method (or similar) in the codecs module. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: python philosophical question - strong vs duck typing
On Wed, 2012-01-04 at 11:30 -0300, Sean Wolfe wrote:
On Tue, Jan 3, 2012 at 7:28 PM, Ben Finney ben+pyt...@benfinney.id.au wrote:
Sean Wolfe ether@gmail.com writes:
Hello everybody, I'm a happy pythonista newly subscribed to the group.
Welcome!
Thanks! and thanks to all, hjaha.
I have a theoretical / philosophical question regarding strong vs duck
typing in Python. Let's say we wanted to type strongly in Python
There may be an unstated assumption there, and your wording confuses me.
yep, probably. I am throwing around terminology a bit. Here's another
attempt --
If I am willing to create some python code, when needed, where when I
create a variable, let's say an integer, that it will be for all time
an integer, and also that a method that returns say a Sprite custom
object, and will for all time return only a Sprite object ... , does
this get me significantly closer to being able to compile to C++?
I'd really recommend looking at Cython - which has optional static
typing and does compile into C / C++ (as a python extension)
More generally, a compiler can perform static analysis on code which
will re-order AST nodes into single constant assignments. I've forgotten
the name but it's something like single static assignment form. When the
return type of functions is known it can lead to known types for
variables.
It's being used heavily in the newest generation of javascript JITs to
speed up generated native code.
However, when a function has multiple return types (e.g. {}.get returns
None if there is no result) then you can't imply the type of the
variable even in this form.
A JIT (such as pypy) can generate the native code for all seen return
types - which is why JITs can in general be more useful to dynamically
typed languages such as Python than compilers.
Another issue is where types can be modified (e.g. in python you can
modify the class of an object at runtime) - dynamic language features
such as this make what counts as a type fairly flexible. JITs are
getting around this using hidden classes (there are lots of other
names for the same thing) - again it would be very difficult to
statically compile this kind of thing to native code.
I am just thinking in my brain about the differences between cpp and
python, and if there is a way to compromise a bit on the python-ness
to get closer to cpp, but still be able to keep a lot of the goodness,
then put in a translator or converter to cpp and gain performance by
using cpp code. Sounds like Rpython, cython, shedskin are doing a lot
or all of this, so lots to study up on.
Yup
Tim Wintle
--
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Re: Make a small function thread safe
On Fri, 2011-12-16 at 05:21 -0800, Brad Tilley wrote:
107 void increment_counter( unsigned int counter )
108 {
109 boost::mutex::scoped_lock lock( counter_lock );
110 ++counter;
111 }
with counter_lock:
counter += 1
... where counter_lock is a threading.Lock instance.
(see docs for the threading module)
Tim
--
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Re: Make a small function thread safe
On Fri, 2011-12-16 at 09:24 -0500, Brad Tilley wrote: So something like this then: import threading shared_container = [] lock = threading.Lock() class thread_example( threading.Thread ): def __init__( self ): threading.Thread.__init__ (self) def run(t): lock shared_container.append(t.name) should be: def run(t): with lock: shared_container.append(t.name) (or lock.acquire() and lock.release() as you mentioned) # main threads = [] for i in xrange(10): thread = thread_example() threads.append(thread) for thread in threads: thread.start() you'll either need to lock again here, or join each thread: for thread in threads: thread.join() for item in shared_container: print item Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: can't decompress data; zlib not available
On Mon, 2011-11-14 at 12:30 -0700, Steve Edlefsen wrote: I did a search on files named python on my machine. There are 23 not including the ones in the Plone buildout-cache in my account. Seems like a lot of applications install their own copy of python. There are also ./usr/lib/x86_64-linux-gnu/libz.so ./usr/lib/libz.so which, I believe, are the zlib libraries. but do you have the headers? On my ubuntu it's /usr/include/zlib.h As Christian pointed out, Ubuntu 11.04 introduced some changes which may have broken the installation - there is a patch on the python bug tracker which will provide a work-around, but it is not going to be applied to 2.6 or lower as they are not actively maintained branches any more. You'll need to run through the steps that the plone installer makes and patch the extracted python directory before it makes it's local python. I've read that you can reinstall python with configure using the --with-zlib option, but configure isn't in /usr/local/Plone/Python-2.6/lib/python2.6/config I think the python interpreter for the command line is the one in /usr/bin/python. Would this be the one I reconfigure for zlib? Should I simply install python from Python-3.2.2.tgz? no - you need to use python2.6 - python3 is effectively a different language. python is a core part of *nix these days, so playing around recompiling the system python can cause a lot of pain. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: can't decompress data; zlib not available
On Sun, 2011-11-13 at 11:17 -0700, Steve Edlefsen wrote: which appears to install zlib when python is reinstalled. Except I can't run make without errors and there is no configuration file. How do I reinstall python to include zlib? Which OS are you on? Linux? BSD? How did you install Plone? First I'd check if there's a module shadowing the builtin zlib module - i.e. if you've got a local file called zlib.py which is getting imported by mistake. Fairly much all *nix systems will have a python installation out of the box - it looks like you need python2.6 I've never had a missing zlib module - but it's possible that it might be missing if you don't have the zlib/deflate headers installed - if they're not available then I'd try installing them and then reinstalling the package you started with. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Use and usefulness of the as syntax
On Sat, 2011-11-12 at 12:56 +0100, candide wrote: So what is the pragmatics of the as syntax ? Another case: try: import json except: import simplejson as json (same goes for several modules where the C implementation may or may not be available) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: The python implementation of the relationships between classes.
On Thu, 2011-11-10 at 22:25 +0800, Jerry Zhang wrote: 2011/11/10 Chris Angelico ros...@gmail.com On Fri, Nov 11, 2011 at 12:58 AM, Jerry Zhang jerry.scofi...@gmail.com wrote: Cls_a: def __init__(self): self.at1 = 1 Cls_b: def __init__(self): self.com1 = Cls_a() def __del__(self): del self.com1 Is it a right implementation for composition? Yes, except that you don't need to explicitly del it. Python (at least, CPython) is reference-counted; your Cls_b object owns a reference to the Cls_a object, so (assuming nothing else has a reference) that Cls_a will be happily cleaned up when the Cls_b is. Python doesn't really talk about composition etc. It's much simpler: everything's an object, and you have references to that object. A named variable is a reference to some object. A member on an object is, too. Whenever an object is expired, all objects that it references lose one reference, and if that was the sole reference, those objects get expired too. It's a change of thinking, perhaps, but not a difficult one in my opinion; and it's so easy to work with when you grok it. Unfortunately there is a difference between composition and aggregation in my real word, and my application really care this since it is trying to simulate this real world model, so my system should track this difference accurately, otherwise the system may not work well. You might want to look into weak references: http://docs.python.org/library/weakref.html Although I agree with Chris that it sounds like your code might be easier with a change of perspective (I've not done much UML, but the way you're describing things sounds like a java-ish way of looking at it to me) For example, a. the Cls_arm and Cls_body may be composition, but not aggregation. My app must ensure that one arm instance only live with one body instance, if the body instance die, the arm instance must die. b. the Cls_auto and the Cls_tyre may be aggregation. One tyre still can live even the auto is dead. That behaviour isn't really hard-coded as part of the language in python, as it's not required for memory management in the same way it would be in C++ or langauges without GCs. As long as no objects other than body objects hold a reference to arm objects then the arm object will be deleted. For The tyre object to be deleted when the auto object is deleted, there would have to be no references left to the tyre object. If there aren't any references then you can't know if it exists or not anyway, so the distinction isn't useful. Meanwhile, I have a ZODB running, which stores all the living objects. The ZODB is append only and stores all objects. Deleting references to an object (which would causes deletion of standard python objects) won't delete it from the zodb, it'll just delete the references. -- http://mail.python.org/mailman/listinfo/python-list
Re: Unit test failing please help
On Fri, 2011-08-26 at 08:35 -0700, lblake wrote: Hi I am new to python I am at bit lost as to why my unit test is failing below is the code and the unit test: class Centipede(object): legs, stomach This doesn't do what you think it does. legs, stomach is a statement and is not defining any variables at all. Presumably you've also got variables named legs and stomach in the module's scope - as I'd expect to see a NameError : name 'legs' is not defined. (I'd also expect a SyntaxError from having an empty __init__ function body) You probably want do write something like this: class Centipede(object): def __init__(self): self.legs = [] self.stomach = [] -- http://mail.python.org/mailman/listinfo/python-list
Re: Questions about GIL and web services from a n00b
On Fri, 2011-04-15 at 12:33 -0400, Chris H wrote: 1. Are you sure you want to use python because threading is not good due to the Global Lock (GIL)? Is this really an issue for multi-threaded web services as seems to be indicated by the articles from a Google search? If not, how do you avoid this issue in a multi-threaded process to take advantage of all the CPU cores available? Is the limiting factor CPU? If it isn't (i.e. you're blocking on IO to/from a web service) then the GIL won't get in your way. If it is, then run as many parallel *processes* as you have cores/CPUs (assuming you're designing an application that can have multiple instances running in parallel so that you can run over multiple servers anyway). Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Fun python 3.2 one-liner
On Tue, 2011-04-05 at 15:38 +0200, Daniel Fetchinson wrote: Yeah, but we don't live in the 80's or 90's anymore and our screens can support xterms (or let alone IDE widows) much wider than 80 characters. I'm using 140 for python these days. Seriously, who would want to limit him/herself to 80 characters in 2011? I'd rather have two files open with 80 columns in them than a single file with 160 columns and have to switch between files. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Non-deterministic output
On Mon, 2011-03-28 at 12:42 +0200, Esben Nielsen wrote: We are making a prototype program in Python. I discovered the output was non-deterministic, i.e. I rerun the program on the same input files and get different output files. We do not use any random calls, nor threading. One of us thought it could be set and dictionaries not always yielding the same results. I, however, would think that given the exact same operations, a set/dictionary would always yield the same results. Am I correct? Or could different runs of the same program yield different results due to, say, different memory locations? If you're using id() at any point (e.g. in __hash__ ) then that would lead to non-deterministic behaviour. obviously so would time.time() etc. -- http://mail.python.org/mailman/listinfo/python-list
Re: why memoizing is faster
On Fri, 2011-03-25 at 09:49 +0100, Andrea Crotti wrote: Terry Reedy tjre...@udel.edu writes: For the reason Stefan explained and hinted above. Try the following instead: def fib_iter(n, _cache = [1,1]): k = len(_cache) if n = k: for i in range(k, n+1): _cache.append(_cache[i-2] + _cache[i-1]) return _cache[n] I don't get what's the difference between that and: def fib_iter(n): ls = [0, 1] for i in range(2, n+1): ls.append(ls[i-2] + ls[i-1]) return ls[n] How can passing a default _cache argument can make such a difference? Default values are initialised at definition time. Since lists are mutable, the _cache variable really is a cache - the following time you call the function it will store all the previous calculations. e.g. def default_value(_cache=[]): ... _cache.append(len(_cache)) ... print _cache ... default_value() [0] default_value() [0, 1] default_value() [0, 1, 2] default_value() [0, 1, 2, 3] -- http://mail.python.org/mailman/listinfo/python-list
Re: Creating Long Lists
On Wed, 2011-02-23 at 13:57 +, Jorgen Grahn wrote: If that's the *only* such use, I'd experiment with writing them as sortable text to file, and run GNU sort (the Unix utility) on the file. It seems to have a clever file-backed sort algorithm. +1 - and experiment with the different flags to sort (compression of intermediate results, intermediate batch size, etc) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Python fails on math
On Tue, 2011-02-22 at 05:20 -0800, christian schulze wrote: [code] from math import e as e from math import sqrt as sqrt 2*e*sqrt(3) - 2*e == 2*e*(sqrt(3) - 1) False [/code] I was wondering what exactly is failing here. The math module? Python, or the IEEE specifications? I'm not sure anything is failing as such - the A==B operator checks if values computed by the expressions A and B are equivalent - it doesn't check if the expressions are equivalent (which you'd obviously need algebra software to attempt). (from the rest of your email I'm assuming you know what's actually happening) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Problems of Symbol Congestion in Computer Languages
On Fri, 2011-02-18 at 12:27 +, Ian wrote: 2) Culture. In the West, a designer will decide the architecture of a major system, and it is a basis for debate and progress. If he gets it wrong, it is not a personal disgrace or career limiting. If it is nearly right, then that is a major success. In Japan, the architecture has to be a debated and agreed. This takes ages, costs lots, and ultimately fails. The failure is because architecture is always a trade off - there is no perfect answer. I find this really interesting - we spend quite a lot of time studying the Toyota production system and seeing how we can do programming work in a similar way, and it's worked fairly well for us (Kanban, Genchi Genbutsu, eliminating Muda Mura, etc). I would have expected Japanese software to have worked quite smoothly, with continuous improvement taking in everybody's opinions etc - although I suppose that if production never starts because the improvements are done to a spec, rather than the product, it would be a massive hindrance. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Use the Source Luke
On Sat, 2011-01-29 at 21:17 -0800, Raymond Hettinger wrote: My thesis is that we can do even better than that by adding direct links from the docs to the relevant code with nice syntax highlighting. +1 - I think the source links are very useful (and thanks for pushing them). However I think the biggest changes that have probably happened with python itself are: (1) More users for whom this is their first language. (2) CS courses / training not teaching C (or pointer-based languages). (2) is especially important IMO - under half of the python developers I have regularly worked with would feel comfortable reading C - so for the other half reading C source code probably isn't going to help them understand exactly what's going on (although in the long run it might help them a lot) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Python documentation too difficult for beginners
On Tue, 2010-11-02 at 04:23 -0700, jk wrote: This (http://epydoc.sourceforge.net/stdlib/) is what I'm talking about. Aaaarrr Why aren't the official docs like this, Because not everyone likes documentation like that. Personally I far prefer the existing documentation to the JavaDoc-style link you sent. and why has it taken me 2 days of searching? All this needs is a search engine behind it and it'd be perfect. Personally I use Google, e.g. list site:docs.python.org to bring up documentation about the list type. -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: stats 0.1a calculator statistics for Python
On Sun, 2010-10-17 at 17:10 +, Steven D'Aprano wrote: I am pleased to announce the first public release of stats for Python. http://pypi.python.org/pypi/stats Quick comment on your sum() function: http://docs.python.org/library/math.html#math.fsum (in 2.6 and above) should do the same thing, but faster. It looks like a useful module though. -- http://mail.python.org/mailman/listinfo/python-list
Re: Speed-up for loops
On Fri, 2010-09-03 at 08:52 +0200, Ulrich Eckhardt wrote: Tim Wintle wrote: [..] under the hood, cpython does something like this (in psudo-code) itterator = xrange(imax) while 1: next_attribute = itterator.next try: i = next_attribute() except: break a = a + 10 There is one thing that strikes me here: The code claims that each iteration there is a lookup of the 'next' field in the iterator. I would expect that this is looked up once before the loop only. Can you confirm that or am I misinterpreting your intention here? As Stefan and Hrvoje have posted, there is a lookup - but in 2.4 and above it's straight off the C structure and compiled efficiently. (I've been looking at 2.3's source recently and had forgotten the optimisation) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Speed-up for loops
On Thu, 2010-09-02 at 12:02 +0200, Michael Kreim wrote: Hi, I was comparing the speed of a simple loop program between Matlab and Python. Unfortunately my Python Code was much slower and I do not understand why. The main reason is that, under the hood, cpython does something like this (in psudo-code) itterator = xrange(imax) while 1: next_attribute = itterator.next try: i = next_attribute() except: break a = a + 10 where C (and I'm assuming matlab) does this: while 1: i = i + 1 if (i imax): break a = a + 10 And the function call in the python is fairly expensive on it's own. Plus it has to do all the standard interpreter stuff for memory management and deciding when to give up the GIL etc. Are there any ways to speed up the for/xrange loop? leaving it in python, no. (well, range is faster in 2.x, but once you get some cache misses due to increased memory usage it's much slower) avoiding iteration by using list comprehensions can help a lot though as it avoids most of the function calls. If you really need to optimise it then you can convert that module to cython by adding a cdef, and then compile it: cdef int i for i in xrange(imax): a = a + 10 print a or you can write it in C it'll run a lot faster. -- http://mail.python.org/mailman/listinfo/python-list
Re: Speed-up for loops
On Thu, 2010-09-02 at 16:13 +0200, Roland Koebler wrote: Hi, Are there any ways to speed up the for/xrange loop? You can use psyco. Assuming you've got a 32-bit machine. -- http://mail.python.org/mailman/listinfo/python-list
Re: Why is python not written in C++ ?
On Sun, 2010-08-01 at 20:01 -0400, Terry Reedy wrote: Not every C programmer knows or wants to learn C++. I think Terry is the only person that's mentioned this - but I'd like to give extra support to it - I for one prefer C to C++ (as someone that writes quite a lot of C extension modules). And as Stephen mentioned - just because C is not an OO language, doesn't mean you can't write OO code in it - you just have to pass an instance of the class method is defined on in as the first parameter (like you do in Python). Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: multitask http server (single-process multi-connection HTTP server)
On Mon, 2010-07-12 at 23:28 +, Luke Kenneth Casson Leighton wrote: On Mon, Jul 12, 2010 at 10:13 PM, geremy condra debat...@gmail.com wrote: On Mon, Jul 12, 2010 at 4:59 PM, lkcl luke.leigh...@gmail.com wrote: there probably exist perfectly good web frameworks that are capable of doing this sort of thing: i feel certain that twisted is one of them. however, the original author of rtmplite decided to rip twisted out and to use multitask.py and i'm one of those strange people that also likes the idea of using 900 lines of awesome elegant code rather than tens of thousands of constantly-moving-target. have you seen nagare: http://www.nagare.org/ I've not used it - but from my understanding it might be what you're looking for (for the http part at least). i hate to think how this would be done using any of the standard MixIns. even if you wrote a special MixIn which did single-instance socket handling, you couldn't use it because the BaseHTTPHandler doesn't cooperate, it has a while True loop on serving connections until they're closed. I started working on something like this once (but I still had threads) - afraid I can't find the code with it in right now. I think it was similar to what you're doing: at least 2 threads - one accepts requests, the other deals with them. * overload BaseHTTPServer.process_request so it just adds connections to a queue. * worker threads fetch connections from the queue and starts working on them. when they want to give up control they raise an exception to bubble back up, and the connection is re-added to the queue along with any persistent data. I seem to remember the annoying bit being having to override SocketServer.finish_request to use an existing handler. - you can fairly easily limit that to process a single session at a time with a shared dictionary or similar. The reason I was doing it was for work that was cached for a short time, but took a while on cache misses - If I noticed that another thread was currently updating the cached version then I raised an exception. (I had code that unlocked the gil, so multi-threaded made sense) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: improving python performance by extension module (64bit)
On Thu, 2010-06-24 at 21:52 -0500, Peng Yu wrote: http://psyco.sourceforge.net/ The above package can improve python program on 32 bit library. But I need to run on 64 bit library. Is there any other module that can help improving the performance of python on 64 bit? As I understand it, Psycho isn't likely to get updated to 64-bit unless someone decides to supply a significant amount of funding to the developers. If you've on a platform where compiling C is easy then I'd highly recommending using Cython for objects that have to be high-performance: http://cython.org/ (It generates C from slightly modified python code - I use it on various 64-bit *nix platforms) Otherwise you could write a standard C extension. The major native-code generation projects that I know of are Pypy and Unladen Swallow, but neither of them are ready for use on 64-bit. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: use python as a calculator
On Thu, 2010-06-24 at 09:33 -0700, ilovesss2004 wrote: On Jun 24, 5:50 pm, Tim Harig user...@ilthio.net wrote: On 2010-06-24, ilovesss2004 yyiillu...@gmail.com wrote: If I run 1.0/10**10 python will return 0 Python 2.6.4 (r264:75706, Dec 11 2009, 23:02:59) [GCC 3.4.6] on linux2 Type help, copyright, credits or license for more information. 1.0/10**10 1e-10 What version are you using? How can I make python return 1e-10? If necessary, cast everything to a float: 1.0/float(10**10) 1e-10 I use python 2.5 Must change version? Is there any other solution? Are you sure you're doing the above? Testing on 2.5: 1.0/10**10 1e-10 ... but if you leave off the .0 it'll think you want integer arithmatic, so return 0. 1/10**10 0 Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Question about NNTPLib
On Tue, 2010-06-08 at 08:24 -0700, Anthony Papillion wrote:
resp, count, first, last, name = server.group('comp.lang.python')
resp, items = server.xover(first, last)
for subject in items:
resp, subject = server.xhdr('subject', first, last)
print subject
While the loop will indeed LOOP through all of the items, the print
statement generates unprintable character (they look like [] in the
terminal window.
[] is the way python prints an empty list.
I don't know NNTPLib, but I'm guessing you don't want to be throwing
away the subject variable, so you either want
for subject in items:
print subject
or
for subject in items:
resp, sub = server.xhdr(subject, first, last)
print sub
- the second will do the same as your current code, I don't know how
NNTPLib returns the subject or what the list it's returning represents.
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Re: OT: Meaning of monkey
On Fri, 2010-03-26 at 12:08 -0400, Mel wrote: Somewhere on the Internet there's a particularly brilliant pop song called Code Monkey. http://www.jonathancoulton.com/2006/04/14/thing-a-week-29-code-monkey/ (he's linked to the mp3 from there) -- http://mail.python.org/mailman/listinfo/python-list
Re: Is it possible to use re2 from Python?
On Wed, 2010-03-24 at 10:44 -0700, _wolf wrote: yes we can! http://github.com/facebook/pyre2 I had made a thin wrapper experiment with here - looks like the version he's shipped is relatively complete and compatible with the re module though. I'll be interested in seeing how well it performs - The wrapper I had been experimenting with ended up far slower than the re module for simple expressions - and the fastest codepaths in RE2 seem to be ones that are incompatible with the API we're used to using in the re module. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: short-circuiting any/all ?
On Mon, 2010-03-22 at 14:45 +, kj wrote: I have a list of items L, and a test function is_invalid that checks the validity of each item. To check that there are no invalid items in L, I could check the value of any(map(is_invalid, L)). But this approach is suboptimal in the sense that, no matter what L is, is_invalid will be executed for all elements of L, any( is_invalid(a) for a in L ) ... generator expression will be lazily computed. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Visual Python programming and decompilers?
On Thu, 2010-03-11 at 20:38 +0200, Ludolph wrote: I decided I can use byteplay3 http://pypi.python.org/pypi/byteplay/ to disassemble the code to workable objects, It even allows me to rebuild the objects to bytecode. So if I define patterns on how python interrupts the source code to bytecode I can visually represent this and also so convert my visual representations back to bytecode. Assuming you're on 2.6 or later, I'd suggest working with the ast module instead: http://docs.python.org/library/ast.html -- http://mail.python.org/mailman/listinfo/python-list
Re: Evaluate my first python script, please
On Thu, 2010-03-04 at 10:39 -0800, Pete Emerson wrote:
I am looking for advice along the lines of an easier way to do this
or a more python way (I'm sure that's asking for trouble!) or
people commonly do this instead or here's a slick trick or oh,
interesting, here's my version to do the same thing.
(1) I would wrap it all in a function
def main():
# your code here
if __name__ == __main__:
main()
(2) PEP8 (python style guidelines) suggests one import per line
(3) I'd use four spaces as tab width
(4)
I'd change this:
for arg in sys.argv[1:]:
for section in hostname.split('.'):
if section == arg:
count = count + 1
break
to something more like:
for section in hostname.split(.):
if section in sys.argv[1:]:
count += 1
(although as you suggested I'd only calculate sys.argv[1:] once)
... or you could replace whole section between the for loop and
hosts.append with:
if sorted(hostname.split(.)) == sorted(sys.argv[1:]):
host.append(hostname)
, at a slight loss of clarity - but I think I'd stick with the more
verbose version personally.
Tim
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Re: Evaluate my first python script, please
On Fri, 2010-03-05 at 07:53 -0800, Pete Emerson wrote: Thanks for your response, further questions inline. On Mar 4, 11:07 am, Tim Wintle tim.win...@teamrubber.com wrote: On Thu, 2010-03-04 at 10:39 -0800, Pete Emerson wrote: I am looking for advice along the lines of an easier way to do this or a more python way (I'm sure that's asking for trouble!) or people commonly do this instead or here's a slick trick or oh, interesting, here's my version to do the same thing. (1) I would wrap it all in a function def main(): # your code here if __name__ == __main__: main() Is this purely aesthetic reasons, or will I appreciate this when I write my own modules, or something else? It's for when you reuse this code. Consider it's in mymodule.py (so run with ./mymodule.py) - if you then make a tests.py (for example) you can import mymodule without it automatically running your code. re-writing it def main(args): #your code if __name__ == __main__: main(sys.argv[1:]) would obviously be more sensible for actually writing tests. ... or you could replace whole section between the for loop and hosts.append with: if sorted(hostname.split(.)) == sorted(sys.argv[1:]): host.append(hostname) This doesn't actually work, because I'm not looking for a one to one mapping of args to sections of hostname, but rather a subset. So passing in 'prod sfo' would register a match for '001.webapp.prod.sfo'. Ah - good point - I guess the the set intersection technique someone else mentioned is best in that case. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: taking python enterprise level?...
On Wed, 2010-03-03 at 20:39 +0100, mk wrote: Hello Tim, Pardon the questions but I haven't had the need to use denormalization yet, so: IOW you basically merged the tables like follows? CREATE TABLE projects ( client_id BIGINT NOT NULL, project_id BIGINT NOT NULL, cost INT, date DATETIME, INDEX(client_id, project_id, date) ); Yup From what you write further in the mail I conclude that you have not eliminated the first table, just made table projects look like I wrote above, right? (and used stored procedures to make sure that both tables contain the relevant data for client_id and project_id columns in both tables) Yup Have you had some other joins on denormalized keys? i.e. in example how the join of hypothetical TableB with projects on projects.client_id behave with such big tables? (bc I assume that you obviously can't denormalize absolutely everything, so this implies the need of doing some joins on denormalized columns like client_id). For these joins (for SELECT statements) this _can_ end up running faster - of course all of this depends on what kind of queries you normally end up getting and the distribution of data in the indexes. I've never written anything that started out with a schema like this, but several have ended up getting denormalised as the projects have matured and query behaviour has been tested assuming you can access the first mapping anyway - ? I'm not clear on what you mean here. I'm refering to not eliminating the first table as you concluded Regards, mk -- http://mail.python.org/mailman/listinfo/python-list
Re: taking python enterprise level?...
On Wed, 2010-03-03 at 16:23 -0500, D'Arcy J.M. Cain wrote: On Wed, 03 Mar 2010 20:39:35 +0100 mk mrk...@gmail.com wrote: If you denormalise the table, and update the first index to be on (client_id, project_id, date) it can end up running far more quickly - Maybe. Don't start with denormalization. Write it properly and only consider changing if profiling suggests that that is your bottleneck. Quite - and I'd add to cache reads as much in front end machines as is permissible in your use case before considering denormalisation. With a decent database engine and proper design it will hardly ever be. I completely agree - I'm simply responding to the request for an example where denormalisation may be a good idea. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: taking python enterprise level?...
On Wed, 2010-03-03 at 17:26 +0100, mk wrote: So there *may* be some evidence that joins are indeed bad in practice. If someone has smth specific/interesting on the subject, please post. I have found joins to cause problems in a few cases - I'm talking about relatively large tables though - roughly order 10^8 rows. I'm on Mysql normally, but that shouldn't make any difference - I've seen almost the same situation on Oracle consider this simple example: /* Table A*/ CREATE TABLE TableA ( project_id BIGINT NOT NULL, cost INT, date DATETIME, PRIMARY KEY (project_id, date) ); /* Table projects */ CREATE TABLE projects ( client_id BIGINT NOT NULL, project_id BIGINT NOT NULL, INDEX(client_id) ); ... now the index on TableA has been optimised for queries against date ranges on specific project ids which should more or less be sequential (under a load of other assumptions) - but that reduces the efficiency of the query under a join with the table projects. If you denormalise the table, and update the first index to be on (client_id, project_id, date) it can end up running far more quickly - assuming you can access the first mapping anyway - so you're still storing the first table, with stored procedures to ensure you still have correct data in all tables. I'm definitely glossing over the details - but I've definitely got situations where I've had to choose denormalisation over purity of data. Rolled-up data tables are other situations - where you know half your queries are grouping by field A it's sometimes a requirement to store that. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: taking python enterprise level?...
On Thu, 2010-02-25 at 02:26 -0800, simn_stv wrote: i plan to build an application, a network based application that i estimate (and seriously hope) would get as many as 100, 000 hits a day (hehe,...my dad always told me to 'AIM HIGH' ;0), not some 'facebook' or anything like it, its mainly for a financial transactions which gets pretty busy... I've got apps running that handle *well* over 100,000 hits / process / day using Python - although some of the heavy lifting is off-loaded to C and MySql - obviously without actually looking at your requirements that doesn't mean much as I don't know how much work each hit requires. Regarding financial transactions - you'll almost certainly want to integrate with something that already has transactional support (sql etc) - so I expect that will bear the brunt of the load so my question is this would anyone have anything that would make python a little less of a serious candidate (cos it already is) and the options may be to use some other languages (maybe java, C (oh God)) I've avoided integrating java with my python (I'm not a big fan of java) - but I've integrated quite a bit of C - it's fairly easy to do, and you can just port the inner loops if you see the need arise. ...i am into a bit of php and building API's in php would not be the hard part, what i am concerned about is scalability and efficiency, well, as far as the 'core' is concerned. I've heard that php can be well scaled (by compiling it to bytecode/C++) - but my preference would always be to python. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: SimpleXMLRPCServer daemon
On Fri, 2010-01-29 at 07:54 -0800, Thomas Allen wrote: The second is that when it does crash, I don't know about it...what would be sufficient as a keep-alive script to restart it? I suppose I could use something like EventMachine (already installed on my server) to watch the PID file if it were deleted reliably. If the server crashes then it clearly won't get around to deleting it's pid file. The way I do it is to use os.kill (with signal 0 IIRC) to check if the process is still alive when the script starts. If it's not then I delete the pid file and carry on starting up. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: ANN: Pymazon 0.1beta released.
On Tue, 2009-12-29 at 19:44 +0100, Chris Colbert wrote: I'm happy to announce the first beta release of Pymazon: a Python implemented alternative to the Amazon mp3 downloader. Pymazon was created specifically to alleviate the issues surrounding the Linux version of the Amazon mp3 downloader (though it should run just fine in Windows too). Thanks! I've been complaining to them for not providing 64-bit binaries (or source) for ages! (Although hats off to them for even providing the number of linux variants they do support) -- http://mail.python.org/mailman/listinfo/python-list
Re: A way to convert RTF to HTML?
On Sun, 2009-12-27 at 20:10 +, Star Glider wrote: the problem is that the one of the fields as text in rich text format, and it needs to be display without the RTF markup, of course. Is there any way to convert RTF to HTML? Depending on how precisely you need to lay it out you might find it relatively easy to do yourself (The spec is available online). I wrote a very simple parser recently as part of a graffle2svg - it ignores most styling options, but applies some of the styles in css. http://code.google.com/p/graffle2svg/ - feel free to take rtf.py from that project under the BSD license if it's helpful. -- http://mail.python.org/mailman/listinfo/python-list
Re: Java-to-Python?
On Fri, 2009-12-18 at 15:44 +0100, Virgil Stokes wrote: I have a rather large Java package for the analysis of networks that I would like to convert to Python. Many of the classes in the Java package are Serializable. Any recommendations on Java-to-Python (2.6) would be appreciated. I used java2python recently with quite a lot of success. I believe it doesn't support newer java features though. http://code.google.com/p/java2python/ -- http://mail.python.org/mailman/listinfo/python-list
Re: Recursion head scratcher
On Wed, 2009-12-02 at 02:07 -0500, Joel Madigan wrote: that it is possible to make it print the path to the finish in the order the steps were taken. That is, the algorithm as written produces: (4,0) (4,1) (3,1) (3,2) (3,3) (2,3) (1,3) (1,2) True Rather than (1,2) (1,3) (2,3) (3,3) (3,2) (3,1) (4,1) (4,0) True Furthermore, he claims it's a one line change without using a stack or any other extra data structure The way I see immediately is a three line change (if you include modifying/removing the existing print statements). It will be one line shorter to print the other order. As a hint - think of what the python interpreter's stack looks like when it's running your code at the moment - that's the stack you're currently using (and need to use) to store the results you print. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: why do I get this behavior from a while loop?
On Fri, 2009-11-27 at 17:06 +0100, S. Chris Colbert wrote: This seems strange to me, but perhaps I am just missing something: snip I would think that second loop should terminate at 9.9, no? I am missing something fundamental? Floating points variables ... http://en.wikipedia.org/wiki/Floating_point 0.1 isn't represented internally, so you haven't actually reached 10. - try comparing that 10. (as it's printed) with 10.0 i.e. print (t == 10.) you'll get False - even though they print the same Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: pointless musings on performance
On Tue, 2009-11-24 at 18:25 +, Antoine Pitrou wrote:
Le Tue, 24 Nov 2009 08:58:40 -0800, Paul Boddie a écrit :
As you
point out, a lot of this RISC vs. CISC analysis (and inferences
drawn
from Python bytecode analysis) is somewhat academic: the cost of the
JUMP_IF_FALSE instruction is likely to be minimal in the context of
all the activity going on to evaluate the bytecodes.
Sorry, I have trouble parsing your sentence. Do you mean bytecode
interpretation overhead is minimal compared to the cost of actual
useful work, or the contrary?
(IMO both are wrong by the way)
Out of interest - has anyone else spotted that the call to
PyObject_IsTrue in the XXX_JUMP_IF_ blocks performs two unnecessary
pointer comparisons?
ceval.c
if (w == Py_True) {
Py_DECREF(w);
FAST_DISPATCH();
}
if (w == Py_False) {
Py_DECREF(w);
JUMPTO(oparg);
FAST_DISPATCH();
}
err = PyObject_IsTrue(w);
Py_DECREF(w);
.
.
.
==
object.c
PyObject_IsTrue(PyObject *v)
{
Py_ssize_t res;
if (v == Py_True)
return 1;
if (v == Py_False)
return 0;
.
.
.
==
Would it be worth in-lining the remaining part of PyObject_IsTrue in
ceval?
Another data point I've heard is that people who have tried a very
crude form of Python-to-C compilation (generating the exact C code
corresponding to a function or method, using Python's C API and
preserving dynamicity without attempting to be clever) have apparently
reached speedups of up to 50% (in other words, twice as fast).
That's roughly what I get with Cython - which does exactly that.
Tim
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Re: Object Relational Mappers are evil (a meditation)
On Fri, 2009-10-16 at 01:01 +0200, Mick Krippendorf wrote: Maybe my English (and my memory) is just not so good. I'm german, and here abnormal and anormal are both negations of normal, but with a slight difference in meaning. anormal means just not normal, whereas the meaning of abnormal is more like perverted. That's of course the better word for the case at hand. From my understanding, the prefix ab- comes from latin (away /away from) - which can also be shortened to a in some usages. (e.g. abnormal) The prefix an - which is more commonly shortened to a comes from the greek - meaning without (e.g. anaerobic ) I agree that abnormal would be the better term here - as it does /can have normalisation information, just not in a standardised manner. -- http://mail.python.org/mailman/listinfo/python-list
Re: Skeletal animation
On Mon, 2009-10-05 at 18:36 +0200, Donn wrote: see: http://www.panda3d.org/wiki/index.php/Attaching_an_Object_to_a_Joint +1 for Panda 3d. Their Node graph is very intuitive for animating joints, and Panda's API is very nice and clean. TimW -- http://mail.python.org/mailman/listinfo/python-list
Re: Entry Level Python Jobs
On Wed, 2009-09-02 at 08:31 -0700, JonathanB wrote: I am a self-taught Python programmer with a liberal arts degree (Cross-cultural studies). I have been programming for several years now and would like to get a job as a python programmer. Unfortunately most of the job posts I have seen are for CS Majors or people with experience. Is there a place I can look for job posts for entry level positions requiring no experience? For the hiring managers, if the job post said CS Major in the requirements, would you consider a liberal arts major at all? Definately not without any experience - but experience doesn't have to come from paid work - coding as a hobby in your free time is what's made all the best developers I know. Some things I personally would expect (and find more important than a CS background) - in order of importance: * Experience (e.g. open source / hobby projects / work) - several years worth. * Problem solving ability * A good comprehension of C, machine code, or something where you have to care about pointers/references. * Basic maths skills. Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Excel edit using python
On Wed, 2009-08-19 at 05:25 -0700, suman wrote: Is there any package to edit the existing excel cell data using python or to create excel charts using python Chris, Chris, where are you? http://www.python-excel.org/ Site provided by Chris Withers: http://mail.python.org/pipermail/python-list/2009-June/716845.html Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: missing 'xor' Boolean operator
On Wed, 2009-07-15 at 02:02 -0700, Jonathan Gardner wrote: On Jul 14, 4:48 pm, Ethan Furman et...@stoneleaf.us wrote: A whole family of supers. :) All the things binary operators can do, Lisp does with 0, 1, 2, or more arguments. +1 n-ary operators are great, but binary operators are just syntactic sugar for functions (which are obviously a generalisation of an n-ary operator in python). The fact that lisp-like languages don't expose this sugar is good for making you think about what you're actually doing, but just like mathematicians use binary (and unary) operators in equations rather than working in the lambda calculus, having that sugar is useful to python. [1] (+) 0 [2] (+ 1) 1 [3] (+ 1 2) 3 [4] (+ 1 2 3) 6 c.f. : sum([]) 0 sum([1]) 1 sum([1,2]) 3 sum([1,2,3]) 6 Once you get used to that, binary operators don't seem so useful anymore. The equivalent in Python is dropping the operators and replacing them with built-in functions that take 0, 1, 2, or more arguments. -- http://mail.python.org/mailman/listinfo/python-list
Dict ordering [was: Re: MySQLdb and ordering of column names in list returned by keys() w/ a DictCursor]
On Thu, 2009-07-02 at 10:32 -0500, Wells Oliver wrote: for row in cursor.fetchall(): print row.keys() What I get is: ['league', 'BB', 'HR', 'IP', 'K', 'H', 'player_id', 'ER'] Neither alphabetical nor the order in which they were specified in the query nor... any seeming order I can suss out. Any ideas? Thanks! keys in a dict are not guaranteed to be in any specific order. It's not specific to the MySQLdb cursor. IIRC it's related to the hashes of the keys (but obviously not in strictly increasing order). You definitely shouldn't rely on the ordering (hence the need for an OrderedDict. e.g. a = ['league', 'BB', 'HR', 'IP', 'K', 'H', 'player_id', 'ER'] for s in a: ... print hash(s) ... -3369365635700083487 8448050754076166 9216055368083080 9344056137084361 9600028874 9216027721 1844482854915224472 8832053061079775 -- http://mail.python.org/mailman/listinfo/python-list
Re: No trees in the stdlib?
On Sat, 2009-06-27 at 06:03 +0100, João Valverde wrote: To answer the question of what I need the BSTs for, without getting into too many boring details it is to merge and sort IP blocklists, that is, large datasets of ranges in the form of (IP address, IP address, string). snip As an anecdotal data point (honestly not trying to raise the Python is slow strawman), I implemented the same algorithm in C and Python, using pyavl. Round numbers were 4 mins vs 4 seconds, against Python (plus pyavl). Out of interest, I recently wrote something similar that imported (a class of) snort rules for blacklisting ip traffic. I could only use the standard library. I ended up writing a simple tree using dict-like objects [1]. Afraid I haven't got a taught CS background to know the name of the structure. (note insertion wasn't the focus, and I didn't bother writing it to handle updates/merges - this is a quick script I run every now and then, so I'm sure it could be done better - I just liked having the standard dict interface for each node) I only had three levels of branching, using the first octet to branch at the root node, the second octet to branch as the second node, and the final two to branch at the third node's depth (since even then that's normally sparse relative to the first two nodes). It works well enough for me - I'm IO bound reading in ip addresses from logs to check against the blacklist, and there is a fair bit of other processing going on for each line. (Obviously I converted the ip addresses to integers before doing all this to avoid hashing strings etc) [1] (As rules could be for any subnet I overloaded some of the dict methods to check against rules on unusual subnets etc. before checking individual ips in the final part) Even considering I'm a worse Python programmer than C programmer, it's a lot. I know many will probably think I tried to do C in Python but that's not the case, at least I don' t think so. Anyway like I said, not really relevant to this discussion. -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythonic way to overwrite a file
On Wed, 2009-06-17 at 14:26 -0400, Cameron Pulsford wrote: This is only supposed to handle text files, so when would reading it all into memory become too much for most computers? I'm guessing there aren't many source files of too great a size. I often use python with server log files - 1Tb of plain-text wouldn't seem too much to me, but it wouldn't fit into ram on many computers ;-) For source files I wouldn't think it would be a problem - but I agree with Jean-Michel, I can imagine running an app like yours over hundreds of source files at once. It wouldn't be nice if I decided to kill the program half way through and found it had died half way through processing a file and lost my code! Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: command line of a process.exe on another host
On Thu, 2009-06-11 at 23:18 +0100, Harry wrote: HI , I have number of process run on different windows servers which run's with different command line parameters. for example process.exe -inputddd statusurl: http://sss.com ., These parameters can vary from host to host. using Psexec I know the PID and process name which are running on these machines, but how I can read the command line parameters of these process. Is there a way to read these command line of the proess via python pls? I'm not sure how well this will work, but it might be worth looking at fabric - which lets you run through ssh onto lots of different machines (so I assume you'll need openssh on those machines) http://docs.fabfile.org/ Haven't used it myself, but I keep meaning to. any feedback appreciated.. thanks Hari -- http://mail.python.org/mailman/listinfo/python-list
Re: install older Python version parallel
On Fri, 2009-06-12 at 00:30 -0700, edexter wrote: I suspect you want to install python 2.4 and then reinstall 2.6 I did that in windows and I don't understand why it wouldn't work in linux It won't normally work on linux these days because most distributions of gnu/linux need python to run the GUI. Put another way it means if something doesn't work how you want it, it's just some python somewhere to change :-) (Trust me, you don't want to remove the system version of python on most linux distributions or on macs) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: unladen swallow: python and llvm
On Sun, 2009-06-07 at 16:40 -0600, Brian wrote: On Fri, Jun 5, 2009 at 3:29 AM, Nick Craig-Wood n...@craig-wood.com wrote: It is an interesting idea for a number of reasons, the main one as far as I'm concerned is that it is more of a port of CPython to a new architecture than a complete re-invention of python (like PyPy / IronPython / jython) so stands a chance of being merged back into CPython. Blatant fanboyism. PyPy also has a chance of being merged back into Python trunk. How? I believe that unladen swallow has already had many of it's optimisations back-ported to CPython, but I can't see how backporting a python interpreter written in python into C is going to be as easy as merging from Unladen swallow, which is (until the llvm part) a branch of CPython. Personally, I think that PyPy is a much better interpreter from a theoretical point of view, and opens up massive possibilities for writing interpreters in general. Unladen Swallow on the other hand is something we can use _now_ - on real work, on real servers. It's a more interesting engineering project, and something that shouldn't require re-writing of existing python code. Tim W -- http://mail.python.org/mailman/listinfo/python-list
Re: While Statement
On Fri, 2009-05-22 at 13:19 +0200, Andre Engels wrote: number/total = 998/999 = 0 number/total*100 = 0*100 = 0 float(number/total*100) = float(0) = 0.0 Change float(number/total*100) to float(number)/total*100 and it should work: I'd use: (number * 100.)/total - works because int * float = float It's a minor thing, but it's much faster to cast implicitly as you miss the python function call overhead - it's no extra work to write, and for numerical things it can really speed things up. a = timeit.Timer(float(200)/5*100) b = timeit.Timer((200*100.)/5) a.timeit(1000) 12.282480955123901 b.timeit(1000) 3.6434230804443359 Tim W -- http://mail.python.org/mailman/listinfo/python-list
Re: python question
On Fri, 2009-05-22 at 05:51 -0700, Craig wrote: I use python 2.6.2 and i useing ubuntu 9.04 not windows. What are you trying to install? is it available in Synaptic package manager? If it's a program written in python, then there may be a file called setup.py. If there is then open a terminal, cd to that directory, and then type: python setup.py install (you may need to do sudo before it) - that will normally automatically compile any extensions written in C hope that helps. Tim W -- http://mail.python.org/mailman/listinfo/python-list
Re: While Statement
On Fri, 2009-05-22 at 09:59 -0400, Dave Angel wrote: Tim Wintle wrote: On Fri, 2009-05-22 at 13:19 +0200, Andre Engels wrote: Change float(number/total*100) to float(number)/total*100 and it should work: I'd use: (number * 100.)/total - works because int * float = float It's the old-timer in me, but I'd avoid the float entirely. You start with ints, and you want to end with ints. So simply do the multiply first, then the divide. number * 100/total Agreed, to be honest I'd not fully read the original post and didn't realise everything was an int. will get the same answer. -- http://mail.python.org/mailman/listinfo/python-list
Re: Self function
On Mon, 2009-05-04 at 19:51 +0100, Arnaud Delobelle wrote: Bearophile, there is a thread on python-ideas about tail-call optimization at the moment. Oooh - haven't noticed that (and don't have time to follow it), but has anyone seen the results I got a week or so ago from briefly playing with a couple of simple optimisations: http://www.teamrubber.com/blog/python-tail-optimisation-using-byteplay/ I was amazed how much you could improve performance by not jumping all over the stack signature.asc Description: This is a digitally signed message part -- http://mail.python.org/mailman/listinfo/python-list
Re: Python interpreter speed
On Sun, 2009-04-19 at 18:11 +0200, Ryniek90 wrote: Hi. Standard Python interpreter's implementation is written in C language. C code while compilation, is compilled into machine code (the fastest code). Python code is compiled into into byte-code which is also some sort of fast machine code. So why Python interpreter is slower than Java VM? Being written in C and compilled into machine code, it should be as fast as C/Asm code. What's wrong with that? I can't remember Java properly, but... Firstly, speed will depend on what you're writing. I dont' actually know how much slower python is, but I'm sure there are some things that run faster in python. for example, the program: #!/usr/bin/python print Hello World is almost certainly faster in python than Java, as the JVM takes much longer to start up. But basically for the actual code execution speed, it's the Virtual machine: Dynamic typing ... is great for productivity, and a great language feature, but it does mean that most operations in the virtual machine have to be wrapped in some kind of type-checking. That adds more and more operations to the work that has to be done to run python code. Just in Time ... is used in the Java VM but not in the standard python VM. It can significantly optimise performance though. There are various people working on adding a JIT to python - I'm most interested in pypy, here's a basic article explaining their current target of adding a tracing JIT ( I believe it's working on a small subset of python): http://morepypy.blogspot.com/2009/03/applying-tracing-jit-to-interpreter.html (Just spotted that there was a new pypy release yesterday if people haven't noticed) You'll also probably notice that many of python's types (list, dict, etc.) might be slower for small sizes than Java's are - that's because they have been optimised to perform efficiently at any size, at the expense of being slightly less efficient than they could be for small sizes) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: The Python standard library and PEP8
On Sun, 2009-04-19 at 18:43 +0200, Emmanuel Surleau wrote: Hi there, Exploring the Python standard library, I was surprised to see that several packages (ConfigParser, logging...) use mixed case for methods all over the place. I assume that they were written back when the Python styling guidelines were not well-defined. I seem to remember there was talk about this on python-dev fairly recently, and basically they wish they had changed more of them in python 3, but as they didn't they are likely to stay. Given that it's rather irritating (not to mention violating the principle of least surprise) to have this inconsistency, wouldn't it make sense to clean up the API by marking old-style, mixed-case methods as deprecated (but keep them around anyway) and add equivalent methods following the lowercase_with_underscores convention? There was some suggestion about introducing synonyms that followed PEP8 and introducing deprecation warnings as you suggested, but I can't remember the outcome. I'd suggest checking the dev archives. -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there a programming language that is combination of Python and Basic?
On Sun, 2009-04-19 at 06:26 +, Steven D'Aprano wrote: (btw, how come nobody has mentioned python bytecode? Most flow control is jumps) I wrote yesterday: GOTO, after all, is just a jump, and we use jumps in Python all the time: raise Exception break continue if... elif... else... for... else... etc. Ah - apologies Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Too early implementation
On Sat, 2009-04-18 at 13:48 +0200, Filip Gruszczyński wrote: So, do you know some good methods to prevent myself from just starting coding (which I like very much) and do some thinking about the problem (which I like a little less ;-))? The Method (If you can call it that) that I use is to have users throw requests at me so fast that they normally have to get backlogged for months at a time (I've got several years worth of backlogged work at the moment). That way by the time I actually start coding I've normally read over the issue several times and approached the problem from various angles ;-) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: [OT] large db question about no joins
On Fri, 2009-04-17 at 21:16 +0100, Martin P. Hellwig wrote: So in other words, just lay out the data which makes the most sense to you, the pain of recreating SQL like logic is there no matter what layout you choose. I have to say that given the amount of pain most people seem to go through when they first learn about relational databases, it seems ironic how much people come to expect that that's the standard way to query data! At the end of the day it's all just one long sequential load of 0s and 1s on disk, and some code somewhere has to do all the logic. (I'm a relational database user btw, but it seems to happen with object database people too - we get so used to our own paradigm that we don't think about other ways of doing the task) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Is there a programming language that is combination of Python and Basic?
On Sun, 2009-04-19 at 05:08 +, Zaphod wrote: Well, most of the Linux kernel is written in C and while there *is* a jump (often JMP) in most asms, you should only do so if you really need to. JSR (jump sub routine) is a better idea in many (most?) cases. Have to say that I feel jump is more than justified in some situations (when it's jumping to within 10-20 lines of the start position, and it's a routine that needs to be highly optimised - I'm thinking tail recursion etc.) (btw, how come nobody has mentioned python bytecode? Most flow control is jumps) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: binary file compare...
On Thu, 2009-04-16 at 21:44 -0700, Adam Olsen wrote: The Wayback Machine has 150 billion pages, so 2**37. Google's index is a bit larger at over a trillion pages, so 2**40. A little closer than I'd like, but that's still 56294995000 to 1 odds of having *any* collisions between *any* of the files. Step up to SHA-256 and it becomes 1915619400 to 1. Sadly, I can't even give you the odds for SHA-512, Qalculate considers that too close to infinite to display. :) That might be true as long as your data is completely uniformly distributed. For the example you give there's: a) a high chance that there's html near the top b) a non-uniform distribution of individual words within the text. c) a non-unifom distribution of all n-grams within the text (as there is in natural language) So it's very far from uniformly distributed. Just about the only situation where I could imagine that holding would be where you are hashing uniformly random data for the sake of testing the hash. I believe the point being made is that comparing hash values is a probabilistic algorithm anyway, which is fine if you're ok with that, but for mission critical software it's crazy. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: python needs leaning stuff from other language
On Sat, 2009-04-04 at 15:36 -0500, Robert Kern wrote: On 2009-04-04 12:07, Tim Wintle wrote: (I didn't expect such strong responses btw!) You are proposing the removal of a general, orthogonal feature (and breaking code in consequence!) just because of a new syntax for a single special case of that feature. That is quite simply ridiculous. Ok, I may have come across a little strongly (was very tired) - I'm not _actually_ saying we should remove it, I'm just pointing out why adding .clear() to lists seems to be unnecessary and slightly messy. The suggested removal of assignments to slices is a theoretical statement. But can you see why your wording might lead the rest of us to believe otherwise? :-) Yes I do - sorry, I tend to check mailing lists at the end of the day when I am quite tired. I think I could argue 'till the cows come home about why adding .clear feels messy to me, bu as it's not my decision in the slightest, I think I will end this thread here ;) Tim -- http://mail.python.org/mailman/listinfo/python-list
Re: Testing dynamic languages
On Sat, 2009-04-04 at 06:37 -0700, grkunt...@gmail.com wrote: If I am writing in Python, since it is dynamically, but strongly typed, I really should check that each parameter is of the expected type, or at least can respond to the method I plan on calling (duck typing). Every call should be wrapped in a try/except statement to prevent the method (and program) from crashing when my method is called with an integer instead of the expected string. At some point you should wrap it in a try/except block - but only at the point where you want the exception to be handled. That will normally be quite far up, and you'll just let the exception travel back up to that point. for example, in a web server type of thing you might have something vaguely like def main: for request in request_itter: try: headers = request.get_headers() dispatch = get_dispatch_fn(headers) response = dispatch(response) except: send_500() You probably then don't need to catch any exceptions in the get_headers, or actual processing methods (unless you are writing to sql or something, when you might want to wrap all statements in a try block, and then put a ROLLBACK; query in the except block (and then raise the caught exception so it goes back the the block above) Is this the experience that Python programmer (of large projects) see? Do you also write unit tests to confirm that the methods actually check for and catch bad parameter types? If I am writing small one- off scripts, I wouldn't worry about it, but if I am writing a large system that must have 99+% uptime without constant monitoring, this really should be verified. I write large applications with a target of 99.9% uptime, and I don't find it a problem. occasionally I have to check parameters, but that's not very often Up for discussion... -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: python needs leaning stuff from other language
On Sat, 2009-04-04 at 02:03 -0500, Robert Kern wrote: Let's be clear: python-ideas seems positive on the idea of adding a .clear() method. *Completely removing* slice assignment has not been broached there. Yup, sorry - I did mean to refer to the initial suggestion, rather than my comments (I didn't expect such strong responses btw!) You are proposing the removal of a general, orthogonal feature (and breaking code in consequence!) just because of a new syntax for a single special case of that feature. That is quite simply ridiculous. Ok, I may have come across a little strongly (was very tired) - I'm not _actually_ saying we should remove it, I'm just pointing out why adding .clear() to lists seems to be unnecessary and slightly messy. The suggested removal of assignments to slices is a theoretical statement. .clear() would be non-orthogonal syntactic sugar. That's okay! Python has syntactic sugar in a number of other places, too! Appropriate doses of syntactic sugar and non-orthogonality are precisely what lets you implement There should be one-- and preferably only one --obvious way to do it. The really key word in that sentence is obvious, not one. FWIW, removing slice assignment would be a gross form of non-orthogonality, too. __getitem__, __setitem__ and __delitem__ should all be able to accept the same indices (or else raise exceptions in the case of immutability). hummm - I'm sure it would be confusing behaviour if it was not available, but I'm not sure how it would be non-orthogonal -- http://mail.python.org/mailman/listinfo/python-list
Re: python needs leaning stuff from other language
On Fri, 2009-04-03 at 13:12 -0400, Mel wrote: I think it would also be better to have One (and prefereably Only One) Obvious Way To Do It. That obvious way, for those who work with Python's ‘set’ and ‘dict’, is a ‘clear’ method. It seems best to have ‘list’ conform with this also. Does that mean a one-off special case rule to forbid slices having a default? Why would it do that? Well, if list.clear were truly and strictly to be the only way to clear the contents of a list, then assigning nothing via the default slice would have to be ruled out. `somelist[:] = []` is just a special case of assignment to a slice generally. agreed. If .clear was to be added then really assignments to slices should be entirely removed. Tim W -- http://mail.python.org/mailman/listinfo/python-list
Re: python needs leaning stuff from other language
On Fri, 2009-04-03 at 18:27 -0500, Robert Kern wrote:
agreed. If .clear was to be added then really assignments to slices
should be entirely removed.
Please tell me you are joking.
Well I'm not joking as such.
I've noticed that python-ideas seems to be positive on the idea, and has
a patch ready for Guido, obviously I'm not that anti it that I'd always
be complaining if it is implemented, I just see it as unnecessary:
http://mail.python.org/pipermail/python-ideas/2009-April/003933.html
(I didn't expect such strong responses btw!)
you can already do:
del mylist[:]
* or *
mylist[:] = []
* or *
mylist = []
which, although semantically similar are different as far as the
interpreter are concerned (since two of them create a new list):
(Python 2.5.2 - don't have a newer version on this machine to check)
{{{
import dis
def f(a):
... del a[:]
...
def g(a):
... a[:] = []
...
def h(a):
... a = []
...
dis.dis(f)
2 0 LOAD_FAST0 (a)
3 DELETE_SLICE+0
4 LOAD_CONST 0 (None)
7 RETURN_VALUE
dis.dis(g)
2 0 BUILD_LIST 0
3 LOAD_FAST0 (a)
6 STORE_SLICE+0
7 LOAD_CONST 0 (None)
10 RETURN_VALUE
dis.dis(h)
2 0 BUILD_LIST 0
3 STORE_FAST 0 (a)
6 LOAD_CONST 0 (None)
9 RETURN_VALUE
}}}
so it seems silly to introduce a *third* formal description of what is
(almost) semantically the same!
My knowledge of the interpreter begins to get fuzzy here, but would this
add extra overhead by the look-ups to the .clear method (really don't
have the time to compile a patched version of trunk to test!) - it might
be a constant change, but it's still a difference to what I believe is
likely to be required to be fairly high-performance when it is used.
e.g.
{{{
def f(a):
... a.clear()
...
dis.dis(f)
2 0 LOAD_FAST0 (a)
3 LOAD_ATTR0 (clear)
6 CALL_FUNCTION0
9 POP_TOP
10 LOAD_CONST 0 (None)
13 RETURN_VALUE
}}}
The current versions at least do two different things quite efficiently
- if you are clearing the list and expect the list to be small / zero
length next time, then (I believe) it's more memory efficient to try
mylist = []
,where
del mylist[:]
will (I'm assuming - correct me if I'm wrong) reduce the size of the
list, but using the clever list memory usage it will scale to a large
size again fairly well.
As for:
Should we also remove .update from dict?
Am I missing something? What is the single statement that is equivalent
to .update (although personally I don't think I have *ever* used .update
- I'm normally using a set for situations where I would require .update)
Oh, and can I have the reference for Raymond Hettinger's blessing
(mentioned in a different branch of this thread)? As far as I can see he
has only (in archives at least) replied to a question about whether it's
worth formalising the request as a PEP, and hasn't entered a vote either
way:
Just ask Guido for his blessing. The implementation is trivial.
http://mail.python.org/pipermail/python-ideas/2009-April/003938.html
Ironically much of my - very limited - knowledge of the interpreter
stems from many of his talks, which were the encouragement to start
actually reading the source for the interpreter!
I'm more than willing to drop my issue if it's voted against, but it
does feel dirty to me to add extra syntax that have completely parallel
semantics.
In general language design (not just programming languages) I personally
take any (provable) requirement for this as a _possible_ problem with
the chosen basis / semantic value function (in 1st order language
terms), although I understand that it is sometimes unavoidable in real
life.
For example, this makes me question the orthogonality of ordered and
collection with semantics dictated by their methods/features.
Proposing that the object:
mylist[a:b:c]
return an iterator that is non-assignable appears to fix this
non-orthogonality as far as I can immediately see (although I am *very*
tired, and haven't thought it through far enough!)
Tim Wintle
--
http://mail.python.org/mailman/listinfo/python-list
Re: is there a way to collect twitts with python?
On Fri, 2009-04-03 at 14:58 -0600, Michael Torrie wrote: Oh wow. If this is what Twitter does to one's ability to articulate clearly, I hope Twitter dies a horrible death and any APIs and Python bindings with it! Thank you, thank you, thank you everyone around me seems to love that thing (twitter), and I still can't work out why (apart from hacks such as using it as a hosted queue for cross-server comms, or receiving cheap sms to your app) Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame and socket.recv
On Wed, 2009-04-01 at 18:45 -0700, Aaron Brady wrote: My game loop looks like this: poll events, get 1 at most send to server wait for server reply render entire frame The look I'm suggesting is: poll events write to (non-blocking) socket render frame check non-blocking socket and add events to the event queue Yes, I am blocking for the data to come down the network. Unfortunately, if I use any prediction, I will have to go back and un-render the previous frame, then redraw with the new information. Sounds like that may have to be re-factored slightly, afraid this is why real-time networked games are tough to make. 40 transmissions per second in each way can't be too much to ask, it's just that they have to alternate, up one, down one. IMO It's very unlikely to be a bandwidth issue. It's more likely to just be a latency issue. I don't understand your solution. I can't picture it for my favorite RTS game or the one I'm writing. Are you saying that the slower machine just jumps ahead, and its user just doesn't have the opportunity to make moves on the omitted frames? a) How much to move etc. is decided based on some real-time solution (not on the number of frames). Ideally all movement methods take a parameter that is a delta in time. (i.e. 1/40th of a second) b) That time is the time that is synced across machines - if machine B has to put it's timer forward 1/50 of a second, you call all the methods above with a timedelta of 1/50 before continuing. c) Obviously things like which frame a sprite is on isn't really necessary for the sake of a game, it's only game state variables that would be required. d) If you end up with jumping objects then you can create ghost objects for the other player's objects. When you get the state of a foreign object, update the real object with the properties, but draw the sprite at the position of your ghost object - and every frame move the ghost object towards the real one a little bit. That gets rid of the effect of jumping from one place to another, but keeps collision detection etc. correct wrt the other player. I am using TCP, socket.SOCK_STREAM. UDP is a potential solution, but it still doesn't fix my main loop. -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: python for loop
On Thu, 2009-04-02 at 06:28 +, Steven D'Aprano wrote:
In set theory, you start by defining the integers like this:
snip
0 = len( {} )
1 = len( {{}} )
2 = len( {{}, {{}}} )
3 = len( {{}, {{}}, {{}, {{}}} )
etc.
not quite len() - surely you mean something like any object along with
an algebra in which the left hand side is equivalent to the right in the
algebra of set theory? - at least for ordinals.
The cardinal is then (for finite numbers) the length of that.
Or, in a pythonic sense (taking 0,1,2,... to be variable names):
0 = set()
1 = set(0)
2 = set(1,0)
3 = set(2,1,0)
3 = set(3,2,1,0)
etc.
How that relates to whether indexing should start at one or zero, I
have
no idea.
so in this sense, range(n) is actually very close to the ordinal value
of 0 (except for being a list and not a set - but it's not in 3.0)
i.e. range(n) returns something very similar to the ordinal n, and
with cardinality n. That seems very sensible to me.
Oh, and speaking of... I'm shocked, SHOCKED I say, that nobody has
given that quote about the compromise of 0.5.
God made the integers, all else is the work of man - Leopold Kronecker
...holding myself back from complaining about integer division in Py3K
when the philosophical question of whether irrational numbers even exist
(in a physics sense) is fairly open.
Tim W
--
http://mail.python.org/mailman/listinfo/python-list
Re: pygame and socket.recv
On Thu, 2009-04-02 at 06:50 -0700, Aaron Brady wrote: It's just that if you register a collision in between the time that one object has changed its position and momentum, and the time you learn about it, you have to retroactively edit the collision, restore hit points, and recalculate the other object's position and momentum, to name a few. So it sounds like what you are trying to do is emulate shared RAM between the two players! The problem being that you have to effectively lock the variables on one machine while the other one reacts. I believe the answer normally used is the client-server architecture. Choose one machine to act as the server somehow, then let that control the entire game state. Both players pass events to this server method (using non-blocking sockets), and render things in the position they believe they are in. I believe that is how all the current RTS games work, certainly how Red Alert worked, and is how all FPS games work (e.g. in unreal there is always a server, and in single player mode the clients are simply bots and the local client application.) You might find the docs for Unreal networking (c. 1999) useful to explain what they did better than I can. http://unreal.epicgames.com/Network.htm -- http://mail.python.org/mailman/listinfo/python-list
Re: python for loop
On Thu, 2009-04-02 at 15:16 -0700, Emile van Sebille wrote: Lou Pecora wrote: Confusion only comes when you try to force the defintion of one of them on the other and then say it's illogical or not natural. Both are natural. Consider the French 'Premiere etage' vs the American 'First Floor' or even in the same language - first floor in English (UK) is very different from first floor in English (US). Emile -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame and socket.recv
On Wed, 2009-04-01 at 17:58 -0700, Aaron Brady wrote: I tried writing a small game on a pygame layer. The graphics are fine, and at the moment, it is not graphics intensive. It is multi- player, and for the communication, I am sending a pickle string across a LAN, once per frame. I'm observing some latency. It seems that socket.recv isn't performing consistently. Not sure I understand the question, are you blocking for the data to come down the network before rendering the next frame? For game programming I've always used select with non-blocking sockets to receive data - and kept the transmissions to UDP to save time (obviously you have to expect some data to be lost). Wire time is always going to have too much latency for a message to be happily passed within the time it takes to render a frame. For syncing time I use a really simple algorithm - both machines send each other their local [game] time every few seconds, and if the received time is ahead of the local time then the receiving machine updates it's time to match - that way they are always out by at most the shortest time it takes for a packet to travel from one to the other. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Another of those is issues.
On Fri, 2009-03-20 at 11:20 -0700, Emanuele D'Arrigo wrote: def aFunction(): ... pass ... f = aFunction f is aFunction True --- Ok, this seems reasonable. Nevertheless, I suspect I shouldn't quite rely on it. You can rely on this in the above - you've just assigned the name f to the same object as aFunction class MyClass(object): ... def myMethod(self): ... pass ... c = MyClass() m = c.myMethod m is c.myMethod False --- What? Why is that? I believe that c.myMethod is actually a new object that's similar to lambda self,*args,**kwargs: MyClass.myMethod(self,*args,**kwargs). ie: The MyClass *instance* has checked if there is an object self.__dict__[myMethod], and when it hasn't found it it creates a new function which wraps the call to the base class up correctly. It's more complicated than this though because you see the same behaviour when checking the method on the class definition. Seem to remember Raymond Hettinger pointing to the code that does this as part of his descriptor tutorial talk at europython - but I can't find the slides to reference. hope that helps, Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: Run on Startup
On Wed, 2009-03-18 at 11:13 -0700, Mike Driscoll wrote: On Mar 18, 1:09 am, Gabriel Genellina gagsl-...@yahoo.com.ar Any decent installer is able to register a program so it runs on startup (InnoSetup, by example). Anyway, if you want to it it yourself, see:http://msdn.microsoft.com/en-us/library/bb776426(VS.85).aspx -- Gabriel Genellina How is putting your program in C:\Program Files stupid? Almost every program I've ever installed on Windows defaults to that location. Putting a link in the Startup folder is kind of silly, I will grant you that. Of course, putting the shortcut there makes it easier for non-techie people to remove it. Otherwise you'll have to hack the registry to stop the startup or run msconfig and stop auto-start there. The reason is that on non-english language versions it's not called C: \Program Files - there's a system setting that installers use to know the correct place to put applications. You should ask windows where it thinks you should put applications, and then put it there. The Startup folder is (I believe) depricated, and I would have guessed that it's not called Startup in other languages. Mike -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: Style question - defining immutable class data members
On Sun, 2009-03-15 at 10:39 -0700, John Posner wrote:
(My apologies if the thread has already covered this.) I believe I understand
the WHAT in this situation, but I don't understand the WHY ...
Is there a beneficial effect of silently creating the instance attribute,
which outweighs the detrimental effects: (1) inconsistency, (2) the
surprising decoupling?
From an end-user point of view (rather than the point of accessing class
methods others mentioned), here are two more reasons:
1) To save memory - there's only one object stored, where an instance
variable will require the same memory every instance (normally)
2) referencing Zope objects (although any persistent object storage will
have the same argument):
(Zope is a web framework that stores data as instances of python classes
in a persistent database.)
let's say you have the class (missing all the boilerplate)
{{{
class ZMyUser():
def __init__(self):
self.lookuplanguage = {\
EN: English
}
self.language = EN
def get_friendly_name(self):
return self.lookuplanguage.get(self.language,--)
}}}
And you create loads of these objects. But then you want to add French
as an option. How do you do that? All the objects have already been
created, so you could either:
* Run through every object in the database one by one and update the
dict as a one-off task (potentially taking a very long time as you force
the computer to pull the entire database off disk)
* Have written lookuplanguage as a class property, so re-initialising
the class will update the definition without any extra overhead.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Style question - defining immutable class data members
On Mon, 2009-03-16 at 04:02 +, Tim Wintle wrote: On Sun, 2009-03-15 at 10:39 -0700, John Posner wrote: Doh, reply out of thread there - I meant to reply to Rhodi's comment further down. Is there any actual advantage to self.attribute picking up Class.attribute instead of raising a NameError? -- http://mail.python.org/mailman/listinfo/python-list
Re: Memory efficient tuple storage
On Fri, 2009-03-13 at 08:59 -0700, psaff...@googlemail.com wrote:
I'm reading in some rather large files (28 files each of 130MB). Each
file is a genome coordinate (chromosome (string) and position (int))
and a data point (float). I want to read these into a list of
coordinates (each a tuple of (chromosome, position)) and a list of
data points.
This has taught me that Python lists are not memory efficient, because
if I use lists it gets through 100MB a second until it hits the swap
space and I have 8GB physical memory in this machine. I can use Python
or numpy arrays for the data points, which is much more manageable.
However, I still need the coordinates. If I don't keep them in a list,
where can I keep them?
If you just have one list, of objects then it's actually relatively
efficient, it's if you have lots of lists that it's inefficient.
I'm not certain without seeing your code (and my biology isn't good
enough to know the answer to my question below)
How many unique chromosome strings do you have (by equivalence)?
If the same chromosome string is being used multiple times then you may
find it more efficient to reference the same string, so you don't need
to have multiple copies of the same string in memory. That may be what
is taking up the space.
i.e. something like (written verbosely)
reference_dict = {}
list_of_coordinates = []
for (chromosome,posn) in my_file:
chromosome = reference_dict.setdefault(chromosome,chromosome)
list_of_coordinates.append((chromosome,posn))
(or something like that)
Tim Wintle
--
http://mail.python.org/mailman/listinfo/python-list
Re: Ban Xah Lee
On Mon, 2009-03-09 at 21:28 -0700, Luis Gonzalez wrote: C'mon guys, Xha Lee always wins, because fools like you get mad at him instead of ignoring him. Here here! -- http://mail.python.org/mailman/listinfo/python-list
Re: Is python worth learning as a second language?
On Mon, 2009-03-09 at 11:19 +, Lie Ryan wrote: Certainly. A programmer that only knows one language would be too limited. Try as many programming language as you can, and especially look for programming languages that have obscenely different paradigm than the language you already know. I completely agree You should know at least a language from each categories (anyone can add if they feel something is missing): - Object oriented, example: C-family, Java, Python, etc - Imperative, example: C-family, Java, Python, etc - Functional, example: Python, Lisp/Scheme, Haskell, etc - Declarative, example: Haskell, Prolog - Logic Programming, example: Prolog, etc - Event driven, example: most GUI sublanguage, etc - Domain specific language, example: Regular Expression (yes it is a programming language, regex parser is a Finite State Machine), SQL, etc - Concurrent programming, example: Erlang, etc - any other paradigms My slight issue with this list that I think things are in too many places. E.g. although you can do functional programming in Python (and many do), I think it's worth trying to learn a language like lisp just for the sake of forcing yourself to fully understand the paradigm. I also think it's worth writing simple programs in a low level - either in assembly, or as Turing/Register machine code. so basically, I still have much to learn... so do I! -- http://mail.python.org/mailman/listinfo/python-list
Re: Chandler, Python, speed
On Sat, 2009-03-07 at 22:05 +, Ville M. Vainio wrote: Alan G Isaac wrote: 3. Chandler is not really an email client. So specifically, which of its functionalities is it slow, and what evidence if any is there that Python is causing this? I remember reading somewhere that the cause of slowness is/was architectural - perhaps it was that chandler was persisting too much stuff to disk, or something. In any case, this might help you google for more detail. I've been using it, and the only major issue I've got is the long shutdown times, which is caused by backing up a copy of _Everything_ to disk, so that upgrades can happen cleanly - sure that's going to be fixed though. Startup time is a bit slow too, but it's designed to be left open all the time, and it's fairly zippy once it's open IMO. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: strings for beginers
On Sat, 2009-03-07 at 12:53 -0800, Sapote wrote: I have an incrementing variable disc_num that I could insert in the line below to create discspanisoX.iso where X is incrementing... burn_cmd = mkisofs -udf -o /home/donkey/discspaniso.iso -graft- points --path-list %s %(temp_list) burn_cmd = mkisofs -udf -o /home/donkey/discspaniso%d.iso -graft-points --path-list %s %(x,temp_list) (i.e. %d for an integer, %s for a string, %f for a float etc.) -- http://mail.python.org/mailman/listinfo/python-list
Re: strings for beginers
On Sat, 2009-03-07 at 21:25 +, Tim Wintle wrote: burn_cmd = mkisofs -udf -o /home/donkey/discspaniso%d.iso -graft-points --path-list %s %(x,temp_list) obviously I meant to say burn_cmd = mkisofs -udf -o /home/donkey/discspaniso% d.iso-graft-points --path-list %s %(disc_num,temp_list) - hadn't noticed the variable was disc_num. Full explanation should be easily found on Google. -- http://mail.python.org/mailman/listinfo/python-list
Re: Themed TK (tk Tile) at last?!
On Sun, 2009-03-08 at 08:37 +1100, Python Nutter wrote: Looks like we finally get tkinter GUI based programs according to Issue# 2983 in Python 3.1a so our programs don't look like something out of early 1980's and can be themed to more closely match the underlying Operating Systems widget set! Wow, I've never used tkinter for a proper app because of it's looks, but I may now once I start using python 2.7 (or 3.1) the desire to use wxWidgets or Qt etc was high because tkinter widgets just look so horrid. How come nobody ever mentions Gtk? Good job python-dev team. And especially Guilherme Polo for doing all the tough work as far as I tell from the issue and the commit logs. Am I right this was a Google Summer of Code project? If so then thanks to Google as well for sponsoring it. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
Re: should i move on to python3
On Sun, 2009-03-08 at 09:15 +1100, Python Nutter wrote: Maybe if everyone shares their own thinking for their own situations it may help. Well, at work I do a mixture of things, some of which require python 2.3 (I know...), and some of which I can write to whatever version I want. I generally use 2.5 for the second group. This is all work that runs live all the time and has money running through it, so I'd rather not risk moving to 3 for *any* of it until: a) any security holes in python 3 have been fixed b) it costs me more to stick with 2.x than to go through all of my code line by line. At home I normally write code for 2.5, as that's what comes with Ubuntu Hardy (on my main, stable, machine), and most users will have 2.5 or 2.6 for quite a long time. For projects that are released, I'm planning to stick to the advice Guido gave at Europython and keep working on 2.5/2.6 in trunk, but automatically generate a 3.x branch using 2to3. I think it's going to be a bit like Java's JVMs (I can barely write Java, but I use some Java projects) - I've got Java 5 and 6 running different applications side by side here. In fact, I've got Sun's JVM for 6 and 5, and IBM's JDK for Java 5 all running. Similarly, on various machines I use CPython 2.3, 2.4, 2.5, 2.6 and Jython 2.2 for various reasons - and I'm certainly planning on using PyPy a large amount once it's stable. I used the Beta of 3.0, but to be honest I haven't used it for anything proper yet. Tim Wintle -- http://mail.python.org/mailman/listinfo/python-list
