Re: os.path.realpath(path) bug on win7 ?
On Sat, Jan 5, 2013 at 10:55 PM, iMath <2281570...@qq.com> wrote:
>
> os.path.realpath(path) bug on win7 ?
>
> Temp.link is a Symbolic link
> Its target location is C:\test\test1
> But
> >>> os.path.realpath(r'C:\Users\SAMSUNG\Temp.link\test2')
> 'C:\\Users\\SAMSUNG\\Temp.link\\test2'
>
> I thought the return value should be ' C:\\test\\test1\\test2'
>
> Is it a bug ? anyone can clear it to me ?
What does os.path.islink('C:/Users/SAMSUNG/Temp.link') report?
Cheers,
Chris
--
http://mail.python.org/mailman/listinfo/python-list
os.path.realpath(path) bug on win7 ?
os.path.realpath(path) bug on win7 ?Temp.link is a Symbolic linkIts target location is C:\test\test1But >>> os.path.realpath(r'C:\Users\SAMSUNG\Temp.link\test2')'C:\\Users\\SAMSUNG\\Temp.link\\test2'I thought the return value should be ' C:\\test\\test1\\test2'Is it a bug ? anyone can clear it to me ?-- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On 01/05/2013 03:35 AM, Sia wrote: I have strings such as: > > tA.-2AG.-2AG,-2ag > or > .+3ACG.+5CAACG.+3ACG.+3ACG > > The plus and minus signs are always followed by a number (say, i). I want python to find each single plus or minus, remove the sign, the number after it and remove i characters after that. So the two strings above become: > > tA.., > and > ... > > How can I do that? > Thanks. I think it's a bit cleaner and nicer to do something similar to itertools.takewhile but takewhile 'eats' a single next value. I was actually doing some stuff that also needed this. I wonder if there's a more elegant, robust way to do this? Here's what I got for now: class BIterator(object): """Iterator with 'buffered' takewhile.""" def __init__(self, seq): self.seq= iter(seq) self.buffer = [] self.end_marker = object() self.last = None def consume(self, n): for _ in range(n): self.next() def next(self): val = self.buffer.pop() if self.buffer else next(self.seq, self.end_marker) self.last = val return val def takewhile(self, test): lst = [] while True: val = self.next() if val is self.end_marker: return lst elif test(val): lst.append(val) else: self.buffer.append(val) return lst def joined_takewhile(self, test): return ''.join(self.takewhile(test)) def done(self): return bool(self.last is self.end_marker) s = ".+3ACG.+5CAACG.+3ACG.+3ACG" not_plusminus = lambda x: x not in "+-" isdigit = lambda x: x.isdigit() def process(s): lst = [] s = BIterator(s) while True: lst.extend(s.takewhile(not_plusminus)) if s.done(): break s.next() n = int(s.joined_takewhile(isdigit)) s.consume(n) return ''.join(lst) print(process(s)) Obviously it assumes the input is well-formed, but the logic would be very easy to change to, for example, check for s.done() after each step. - mitya -- Lark's Tongue Guide to Python: http://lightbird.net/larks/ -- http://mail.python.org/mailman/listinfo/python-list
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SOLUTIONS MANUAL TO A Course in Modern Mathematical Physics by Peter Szekeres
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Good Python IDE
Hello All, I am recently started couple of projects in Python, one in Python GTK and one in Python Qt. I want a good IDE (For Windows ) for Python which gives support for Python as well as PyGtk and PyQt. Features I am looking for * Support for Core Python Auto-completion. * Support for PyGtk and PyQt * Support for either Bazaar (preferred) or CVS Thanks ! - Sourabh -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming philosophy
The main philosophy behind python (according to me) is rapid application development. The python gives you convinent and powerful tool to develop sophisticated application rapidly. You can find more details on http://www.python.org/about/success/ http://www.python.org/about/success/#rapid-application-development Have a great python time. - Sourabh -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming philosophy
chaouche yacine於 2013年1月6日星期日UTC+8上午6時34分38秒寫道： > The compiler reads your source code and parses it into parse trees. This is > first step. It then takes the parse trees and transform them into abstract > syntax trees, which are like a DOM tree in an HTML file, and then transform > that AST into a control flow graph, and finally a bytecode is produced out of > that control flow graph. The pyc files you see are this bytecode, so they are > produced at the end. Anytime you edit your .py file, a new .pyc file is > created if you invoke the python interpreter myfile.py on the former. If your > .py file doesn't change, the .pyc file stays the same. > > Just like with java, this allows you to write a single .py file that can work > on any platform without changing the source file, because all the cross > platform issues are handled by the virtual machine. > > > > > > From: Nac Temha > To: pytho...@python.org > Sent: Saturday, January 5, 2013 11:05 PM > Subject: Python programming philosophy > > > Hello, > > > > I want to learn working principle of python as broadly. How to interpret the > python? For example, what is pyc files and when does it occur? > Can you explain them? Thanks in advance. > -- > http://mail.python.org/mailman/listinfo/python-list Yes, check JYTHON tutorials to understand dynamic types. Java is still a fixed type computer language. -- http://mail.python.org/mailman/listinfo/python-list
A question about thrift performance.
Hi, all
I have issue of thrift-performance in python, does anyone has an experience on
thrift-in-python?
My question in stackoverflow:
http://stackoverflow.com/questions/14171227/why-is-thrift-binary-protocol-serialization-so-much-slow
Copy the question to here(open stackoverflow to check pretty-print question
content):
I'm newbie on thrift. I wrote a thrift server in python, also client in python
too.
Here is my thrift defination:
struct RatingByReport {
1: required string ticker,
2: required i32 cnt_institution,
3: optional list strong_buy,
4: optional list buy,
5: optional list neutral,
6: optional list sell,
7: optional list strong_sell,
8: optional i32 cnt_maintain,
9: optional i32 cnt_upgrade,
10: optional i32 cnt_downgrade,
11: optional i32 avg_score,
12: optional string adjustment
}
struct TableRatingByReport {
1: required list head,
2: required list body,
3: optional struct.CadaTranslation translation
}
service china{
void ping(),
TableRatingByReport rating_byreport(1:string ticker) throws
(1:struct.CadaInternalError error)
}
Here is my server side:
handler = StockChinaHandler()
processor = china.Processor(handler)
#startup()
transport = TSocket.TServerSocket(port=30303)
tfactory = TTransport.TBufferedTransportFactory()
pfactory = TBinaryProtocol.TBinaryProtocolFactory()
server = TServer.TSimpleServer(processor, transport, tfactory, pfactory)
#server = TProcessPoolServer.TProcessPoolServer(processor, transport,
#tfactory, pfactory)
print "Start server..."
import cProfile
print >>open('/tmp/test.log', 'w'), cProfile.run('server.serve()',
sort='cumulative')
#server.serve()
print "done!"
Client side:
# Make socket
transport = TSocket.TSocket('localhost', 30303)
# Buffering is critical. Raw sockets are very slow
transport = TTransport.TBufferedTransport(transport)
# Wrap in a protocol
protocol = TBinaryProtocol.TBinaryProtocol(transport)
# Create a client to use the protocol encoder
client = china.Client(protocol)
# Connect!
transport.open()
client.ping()
print "ping()"
print msg
msg = client.rating_byreport('2012-01-04')
print msg
transport.close()
cProfile result:
ncalls tottime percall cumtime percall filename:lineno(function)
10.0000.000 230.968 230.968 :1()
10.0000.000 230.968 230.968 TServer.py:74(serve)
30.0000.000 225.967 75.322 TSocket.py:172(accept)
30.0000.000 225.967 75.322 socket.py:194(accept)
3 225.967 75.322 225.967 75.322 {method 'accept' of
'_socket.socket' objects}
50.0030.0014.9930.999 china.py:140(process)
10.0000.0003.2003.200
china.py:177(process_rating_byreport)
10.0000.0002.3662.366 china.py:500(write)
10.0030.0032.3662.366 ttypes.py:515(write)
14550.2610.0002.3630.002 ttypes.py:364(write)
160.2460.0001.9950.000 TCompactProtocol.py:38(nested)
1458800.2980.0001.6400.000
TCompactProtocol.py:255(__writeString)
181.3700.0761.3700.076 {method 'recv' of
'_socket.socket' objects}
50.0000.0001.2920.258
TCompactProtocol.py:306(readMessageBegin)
130.0000.0001.2920.099
TCompactProtocol.py:286(__readUByte)
260.0000.0001.2910.050 TTransport.py:54(readAll)
260.0000.0001.2910.050 TTransport.py:154(read)
50.0000.0001.2910.258 TSocket.py:101(read)
In my case, TableRatingByReport instance got a body with 1400 rows(list\), and
It cost over 3 seconds(function *process_rating_byreport*, which is auto
generate by thift) to generate binnary content. I don't know why it is so slow.
Using json to serialize the same data, It's only spend less than 200 ms.
I'm wondering did I use the uncorrect way to manipulate thrift?
Thanks.
--
http://mail.python.org/mailman/listinfo/python-list
Re: Python programming philosophy
The compiler reads your source code and parses it into parse trees. This is first step. It then takes the parse trees and transform them into abstract syntax trees, which are like a DOM tree in an HTML file, and then transform that AST into a control flow graph, and finally a bytecode is produced out of that control flow graph. The pyc files you see are this bytecode, so they are produced at the end. Anytime you edit your .py file, a new .pyc file is created if you invoke the python interpreter myfile.py on the former. If your .py file doesn't change, the .pyc file stays the same. Just like with java, this allows you to write a single .py file that can work on any platform without changing the source file, because all the cross platform issues are handled by the virtual machine. From: Nac Temha To: python-list@python.org Sent: Saturday, January 5, 2013 11:05 PM Subject: Python programming philosophy Hello, I want to learn working principle of python as broadly. How to interpret the python? For example, what is pyc files and when does it occur? Can you explain them? Thanks in advance. -- http://mail.python.org/mailman/listinfo/python-list-- http://mail.python.org/mailman/listinfo/python-list
Re: import of ttk
On 1/5/2013 2:21 PM, Verde Denim wrote: On 01/04/2013 11:39 PM, Terry Reedy wrote: On 1/4/2013 11:02 PM, Verde Denim wrote: In reading through one of the learning articles, I have a bit of code that imports ttk, but I apparently don't have this installed. I've looked up the svn checkout for python-tk, and have checked it out (read-only), but still get the same error. I'm running 2.6.6 python, if that helps. Upgrade to the latest 2.7 or even 3.3 if at all possible. Show the line of code that did not work and the traceback. What system are you running on and what tcl/tk installation does it have? ttk is included with any 8.5 installation. tile is often included with 8.4 installations and should be picked up as well. The article I'm looking at is here - http://www.zetcode.com/gui/tkinter/introduction/ The line is - 16 from ttk import Frame, Button, Style $ python tkinter_tut1.py Traceback (most recent call last): File "tkinter_tut1.py", line 16, in from ttk import Frame, Button, Style ImportError: No module named ttk I'm running on Debian Squeeze, and do show both 8.4 and 8.5 of tcl On my Windows 2.7 installation, directory /Lib contains directory /lib-tk (which is added to the path). /lib-tk contains files Tkinter.py and ttk.py, among others. If you have ttk.py, then I do not think you should get that specific message; if there were a problem finding tcl/tk, it should say something else. If you do not have that file, as it seems, then your installation is incomplete. So check your /Lib/lib-tk. If you do not know where it is import sys print(sys.path) Portability note: In 3.x, /lib-tk was renamed /tkinter and removed from the path. Tkinter.py was renamed __init__.py to make the renamed /tkinter an importable package. So 'import Tkinter becomes 'import tkinter', while 'import ttk', etcetera, is now 'import tkinter.ttk', etcetera. 2to3 should make the fixes. -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Python programming philosophy
On Sun, Jan 6, 2013 at 9:05 AM, Nac Temha wrote: > Hello, > > I want to learn working principle of python as broadly. How to interpret the > python? For example, what is pyc files and when does it occur? > Can you explain them? Thanks in advance. The pyc files aren't really a philosophical point, they're just a cache of the compiled versions of .py files - the assumption being that if you import it as a module once, chances are you'll import it again later, and libraries tend not to change much. For the philosophy of Python, type this at the interactive prompt: import this ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
On 01/05/2013 04:55 PM, Terry Reedy wrote: > On 1/5/2013 1:58 PM, Dave Angel wrote: > >> If you're trying to make a faster loop, then I suggest you look into set >> differences. Turn both lists into sets, and subtract them. Something >> like (untested): >> >> result = not bool( set(lst1) - set(lst2) ) > > This does not return False as soon as an item in set1 is found that is > not in set2. > > set(lst1) < set(lst2) > > will, and directly return False/True. The OP is trying to compute the > lst1 < lst2, where lst1 and lst2 are interpreted as sets, rather than > as sequences with the lexicographic ordering default. > Thanks. I wasn't aware that sets supported ordered comparison that way, though it makes perfect sense now that you point it out. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Python programming philosophy
Hello, I want to learn working principle of python as broadly. How to interpret the python? For example, what is pyc files and when does it occur? Can you explain them? Thanks in advance. -- http://mail.python.org/mailman/listinfo/python-list
Re: python wiki gone?
On 1/5/2013 2:59 PM, Andrew Berg wrote: On 2013.01.05 13:07, Lee Harr wrote: When I go to wiki.python.org I get redirected to http://wiki.python.org/moin/ which is 404 Not Found. There's a security issue with moinmoin. The Python wiki is not the only wiki offline for this reason. For anyone doing such a thing in the future: A replacement page "The Python wiki is off-line for maintenance." would have been nice. -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
On 1/5/2013 1:25 PM, Asim wrote: Hi All The following reduce expression checks if every element of list lst1 is present in list lst2. It works as expected for integer lists but for lists of strings, it always returns False. reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) reduce(lambda x, y: x and (y in lst2), lst1, True) would work, but as other have said, you want to stops at the first False, which all() does, and if lst2 is a list of hashable items, x in set for O(1) rather than O(n) check. Moreover, for the lists of strings the following for-loop gives correct results when the above reduce expression doesn't. You should include data for testing. isSublist = True > for i in lst1: > isSublist = isSublist and (i in> lst2) If isSublist remains True, there is no need to rebind it > if not isSublist: > isSublist = False Setting isSublist False when it is False is redundant. break Taking into account the comments: def is_sublist(a, b): b = set(b) # optional, depending on contents for item in a: if item not in b: return False else: # not needed because return above return True The code for all() is similar, except that all takes an iterable, so that the testing is done as part of the input iterable. def all(iterable): it = iter(iterable): for item in it: if not it: return False: else: return True def issublist(a, b): b = set(b) return all(item in b for item in a) -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
On 1/5/2013 1:58 PM, Dave Angel wrote: If you're trying to make a faster loop, then I suggest you look into set differences. Turn both lists into sets, and subtract them. Something like (untested): result = not bool( set(lst1) - set(lst2) ) This does not return False as soon as an item in set1 is found that is not in set2. set(lst1) < set(lst2) will, and directly return False/True. The OP is trying to compute the lst1 < lst2, where lst1 and lst2 are interpreted as sets, rather than as sequences with the lexicographic ordering default. -- Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
In article , Chris Angelico wrote: > On Sun, Jan 6, 2013 at 7:04 AM, Ian Kelly wrote: > > On Sat, Jan 5, 2013 at 8:57 AM, Chris Angelico wrote: > >> You miss my point, though. I went for simple Pythonic code, and never > >> measured its performance, on the expectation that it's "good enough". > >> Written in C, the state machine is probably WAY faster than splitting > >> and then iterating. My C++ MUD client uses code similar to that to > >> parse TELNET and ANSI codes from a stream of bytes in a socket (and > >> one of its "states" is that there's no more data available, so wait on > >> the socket); the rewrite in a high level language divides the string > >> on "\xFF" for TELNET and "\x1B" for ANSI, working them separately, and > >> then afterward splits on "\n" to divide into lines. The code's much > >> less convoluted, it's easier to test different parts (because I can > >> simply call the ANSI parser with a block of text), and on a modern > >> computer, you can't see the performance difference (since you spend > >> most of your time waiting for socket data anyway). > > > > Anecdotally and somewhat off-topic, when I wrote my own MUD client in > > Python, I implemented both TELNET and ANSI parsing in Python using a > > state machine processing one byte at a time (actually two state > > machines - one at the protocol layer and one at the client layer; the > > telnet module is a modified version of the twisted.conch.telnet > > module). I was worried that the processing would be too slow in > > Python. When I got it running, it turned out that there was a > > noticeable lag between input being received and displayed. But when I > > profiled the issue it actually turned out that the rich text control I > > was using, which was written in C++, wasn't able to handle a large > > buffer gracefully. The parsing code in Python did just fine and > > didn't contribute to the lag issue at all. > > The opposite decision, the same result. Performance was *good enough*. > With Gypsum, my early performance problems were almost completely > solved by properly handling the expose-event and only painting the > parts that changed (I don't use a rich text control, I use a > GTK2.DrawingArea). Text processing of something that's come over a > network is seldom a problem; if it were, we'd see noticeably slower > downloads over HTTPS than HTTP, and that just doesn't happen. I think > (though I can't prove) that crypto written in C is probably more > expensive than ANSI parsing written in Python. > > ChrisA It's rare to find applications these days that are truly CPU bound. Once you've used some reasonable algorithm, i.e. not done anything in O(n^2) that could have been done in O(n) or O(n log n), you will more often run up against I/O speed, database speed, network latency, memory exhaustion, or some such as the reason your code is too slow. The upshot of this is that for most things, Python (even though it runs an order of magnitude slower than C), will always be *good enough*. I'm sure I've mentioned this before, but the application code for Songza.com is 100% Python. We pretty much can't even measure how much CPU time is spent running Python code. Everything is database, network, and (occasionally) disk throughput. -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
Asim writes: > Hi All > > The following reduce expression checks if every element of list lst1 > is present in list lst2. It works as expected for integer lists but > for lists of strings, it always returns False. > >reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) Possibly this: >>> True in [3, 1, 4] True >>> True in ["3", "1", "4"] False Since reduce(f, [a, b, c]) == f(f(a,b),c), your x will be True or False except in the innermost call where it is the first element of the list being reduced. It doesn't really work with integers either. Only in certain special cases: very short lst1, or True in lst2. > Moreover, for the lists of strings the following for-loop gives > correct results when the above reduce expression doesn't. > >isSublist = True >for i in lst1: > isSublist = isSublist and (i in lst2) > if not isSublist: > isSublist = False > break > > Can someone help me understand why? Consider reduce(lambda x, y: x and (y in whatever), ys, True). Maybe also consider all(y in whatever for y in ys). -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On Sun, Jan 6, 2013 at 7:04 AM, Ian Kelly wrote: > On Sat, Jan 5, 2013 at 8:57 AM, Chris Angelico wrote: >> You miss my point, though. I went for simple Pythonic code, and never >> measured its performance, on the expectation that it's "good enough". >> Written in C, the state machine is probably WAY faster than splitting >> and then iterating. My C++ MUD client uses code similar to that to >> parse TELNET and ANSI codes from a stream of bytes in a socket (and >> one of its "states" is that there's no more data available, so wait on >> the socket); the rewrite in a high level language divides the string >> on "\xFF" for TELNET and "\x1B" for ANSI, working them separately, and >> then afterward splits on "\n" to divide into lines. The code's much >> less convoluted, it's easier to test different parts (because I can >> simply call the ANSI parser with a block of text), and on a modern >> computer, you can't see the performance difference (since you spend >> most of your time waiting for socket data anyway). > > Anecdotally and somewhat off-topic, when I wrote my own MUD client in > Python, I implemented both TELNET and ANSI parsing in Python using a > state machine processing one byte at a time (actually two state > machines - one at the protocol layer and one at the client layer; the > telnet module is a modified version of the twisted.conch.telnet > module). I was worried that the processing would be too slow in > Python. When I got it running, it turned out that there was a > noticeable lag between input being received and displayed. But when I > profiled the issue it actually turned out that the rich text control I > was using, which was written in C++, wasn't able to handle a large > buffer gracefully. The parsing code in Python did just fine and > didn't contribute to the lag issue at all. The opposite decision, the same result. Performance was *good enough*. With Gypsum, my early performance problems were almost completely solved by properly handling the expose-event and only painting the parts that changed (I don't use a rich text control, I use a GTK2.DrawingArea). Text processing of something that's come over a network is seldom a problem; if it were, we'd see noticeably slower downloads over HTTPS than HTTP, and that just doesn't happen. I think (though I can't prove) that crypto written in C is probably more expensive than ANSI parsing written in Python. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On Sat, Jan 5, 2013 at 8:57 AM, Chris Angelico wrote: > You miss my point, though. I went for simple Pythonic code, and never > measured its performance, on the expectation that it's "good enough". > Written in C, the state machine is probably WAY faster than splitting > and then iterating. My C++ MUD client uses code similar to that to > parse TELNET and ANSI codes from a stream of bytes in a socket (and > one of its "states" is that there's no more data available, so wait on > the socket); the rewrite in a high level language divides the string > on "\xFF" for TELNET and "\x1B" for ANSI, working them separately, and > then afterward splits on "\n" to divide into lines. The code's much > less convoluted, it's easier to test different parts (because I can > simply call the ANSI parser with a block of text), and on a modern > computer, you can't see the performance difference (since you spend > most of your time waiting for socket data anyway). Anecdotally and somewhat off-topic, when I wrote my own MUD client in Python, I implemented both TELNET and ANSI parsing in Python using a state machine processing one byte at a time (actually two state machines - one at the protocol layer and one at the client layer; the telnet module is a modified version of the twisted.conch.telnet module). I was worried that the processing would be too slow in Python. When I got it running, it turned out that there was a noticeable lag between input being received and displayed. But when I profiled the issue it actually turned out that the rich text control I was using, which was written in C++, wasn't able to handle a large buffer gracefully. The parsing code in Python did just fine and didn't contribute to the lag issue at all. -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
Because reduce doesn't do what you want. You'd want "all". L1 = [1,2,3] L2 = ["A1","B2","C3",1,2,3] print all((x in L2 for x in L1)) # prints True L3 = ["A1","B2","C3"] print all((x in L2 for x in L3)) # prints True - Original Message - From: Asim To: python-list@python.org Cc: Sent: Saturday, January 5, 2013 7:25 PM Subject: reduce expression to test sublist Hi All The following reduce expression checks if every element of list lst1 is present in list lst2. It works as expected for integer lists but for lists of strings, it always returns False. reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) Moreover, for the lists of strings the following for-loop gives correct results when the above reduce expression doesn't. isSublist = True for i in lst1: isSublist = isSublist and (i in lst2) if not isSublist: isSublist = False break Can someone help me understand why? Asim -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
Re: python wiki gone?
On 2013.01.05 13:07, Lee Harr wrote: > When I go to wiki.python.org I get redirected to > http://wiki.python.org/moin/ > which is 404 Not Found. There's a security issue with moinmoin. The Python wiki is not the only wiki offline for this reason. -- CPython 3.3.0 | Windows NT 6.2.9200.16461 / FreeBSD 9.1-RELEASE -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame - importing GL - very bad...
On 01/05/2013 02:27 PM, Chris Angelico wrote: On Sun, Jan 6, 2013 at 12:06 AM, someone wrote: In any case I think we understand each other. That's one of the links I just posted :) It's not just a naming difference, though. With Pascal's pass-by-reference semantics, this code would act differently: def foo(x): x = 5 a = 2 foo(a) print(a) Python prints 2, because the assignment to x just rebinds the name inside foo. True pass-by-reference actually changes the caller's variable. C can achieve this by means of pointers; in Python, you can I thought that python also used "true" pass-by-reference, although I haven't figured out exactly when I have this problem. I can just see that sometimes I get this problem and then I need to copy the variable, if I don't want the original data of the variable to be overwritten... pass and mutate a list, thus: def foo(x): x[0] = 5 # Dereference the pointer, kinda x=[None] # Declare a pointer variable, ish x[0] = 2 foo(x) # Don't forget to drop the [0] when passing the pointer to another function print(x[0]) # Prints 5. See? We have pass-by-reference! Yes, something like this has happened to me in my python code... Not sure if my example was exactly like this, but I remember something where I found this to be a problem that I had to fix. But otherwise, rebinding names in the function has no effect on anything outside. Among other things, this guarantees that, in any hmm. ok So it's not true pass-by-reference like I thought... That's interesting. situation, a name referencing an object can be perfectly substituted for any other name referencing the same object, or any other way of accessing the object. def foo(lst): lst[0]=len(lst) x = [10,20,30] y = x foo(x) # These two... foo(y) # ... are identical! This is something I've experienced from my own coding, I think... This is a philosophy that extends through the rest of the language. A function returning a list can be directly dereferenced, as can a list literal: def foo(): return [0,1,4,9,16] print( ["Hello","world!","Testing","Testing","One","Two","Three"][foo()[2]] ) That prints out "One"... I think I understand - that's interesting too... This is a flexibility and power that just doesn't exist in many older languages (C and PHP, I'm looking at you). Object semantics make more sense than any other system for a modern high level language, which is why many of them do things that way. I agree, that I think python is really great and it's fast to do something useful. Not sure I still understand exactly all aspects of this pass-by-value and by-references, but in any case I know enough to watch out for this problem and once I see I have a problem, I can also take care of it and solve it by making a copy. I think maybe after 3-6-9 months more of working with python, I should be fully confident with this. Thanks for taking the time to explain a bit of this to me... -- http://mail.python.org/mailman/listinfo/python-list
Re: import of ttk
On 01/04/2013 11:39 PM, Terry Reedy wrote: > On 1/4/2013 11:02 PM, Verde Denim wrote: >> In reading through one of the learning articles, I have a bit of code >> that imports ttk, but I apparently don't have this installed. I've >> looked up the svn checkout for python-tk, and have checked it out >> (read-only), but still get the same error. I'm running 2.6.6 python, if >> that helps. > > Show the line of code that did not work and the traceback. What system > are you running on and what tcl/tk installation does it have? ttk is > included with any 8.5 installation. tile is often included with 8.4 > installations and should be picked up as well. > > The article I'm looking at is here - >> http://www.zetcode.com/gui/tkinter/introduction/ > > The line is - 16 from ttk import Frame, Button, Style $ python tkinter_tut1.py Traceback (most recent call last): File "tkinter_tut1.py", line 16, in from ttk import Frame, Button, Style ImportError: No module named ttk I'm running on Debian Squeeze, and do show both 8.4 and 8.5 of tcl -- http://mail.python.org/mailman/listinfo/python-list
python wiki gone?
Have I just happened across wiki.python.org at a bad time, or is the wiki gone? When I go to wiki.python.org I get redirected to http://wiki.python.org/moin/ which is 404 Not Found. -- http://mail.python.org/mailman/listinfo/python-list
Re: reduce expression to test sublist
On 01/05/2013 01:25 PM, Asim wrote: > Hi All > > The following reduce expression checks if every element of list lst1 is > present in list lst2. It works as expected for integer lists but for lists > of strings, it always returns False. > >reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) > > Moreover, for the lists of strings the following for-loop gives correct > results when the above reduce expression doesn't. > >isSublist = True >for i in lst1: > isSublist = isSublist and (i in lst2) > if not isSublist: > isSublist = False > break > > > Can someone help me understand why? > > Asim reduce only makes sense if the value you're reducing to is of the same type as the elements of the list you're iterating over. Since your lambda expression returns a boolean (True or False), it'll seem to work on some lists of ints. That's just a coincidence since the bools are compatible with ints, and maybe you've got a 0 or 1 in the list. But if your list has only strings, then True will never be that list. If you're trying to make a faster loop, then I suggest you look into set differences. Turn both lists into sets, and subtract them. Something like (untested): result = not bool( set(lst1) - set(lst2) ) -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On 01/05/13 11:24, Tim Chase wrote: I don't know how this version times out: import re r = re.compile(r"[-+](\d+)([^-+]*)") def modify(m): result = m.group(2)[int(m.group(1)):] return result Doh, I intended to change this after testing, making it just returm m.group(2)[int(m.group(1)):] rather than expending an intermediate variable I used for testing -tkc -- http://mail.python.org/mailman/listinfo/python-list
reduce expression to test sublist
Hi All The following reduce expression checks if every element of list lst1 is present in list lst2. It works as expected for integer lists but for lists of strings, it always returns False. reduce( lambda x,y: (x in lst2) and (y in lst2), lst1) Moreover, for the lists of strings the following for-loop gives correct results when the above reduce expression doesn't. isSublist = True for i in lst1: isSublist = isSublist and (i in lst2) if not isSublist: isSublist = False break Can someone help me understand why? Asim -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On 01/05/13 02:35, Sia wrote:
I have strings such as:
tA.-2AG.-2AG,-2ag
or
.+3ACG.+5CAACG.+3ACG.+3ACG
The plus and minus signs are always followed by a number (say, i). I want
python to find each single plus or minus, remove the sign, the number after it
and remove i characters after that. So the two strings above become:
tA..,
and
...
With the same caveat as Frank posted about the second one being
"" (4 dots), I don't know how this version times out:
import re
r = re.compile(r"[-+](\d+)([^-+]*)")
def modify(m):
result = m.group(2)[int(m.group(1)):]
return result
for test, expected in (
("tA.-2AG.-2AG,-2ag", "tA..,"),
(".+3ACG.+5CAACG.+3ACG.+3ACG", ""),
):
s = r.sub(modify, test)
print "%r -> %r (%r)" % (
test, s, expected
)
assert s == expected, "Nope"
(it passes the tests as modified to "")
-tkc
--
http://mail.python.org/mailman/listinfo/python-list
Re: Yet another attempt at a safe eval() call
On Saturday, January 5, 2013 8:17:16 AM UTC-8, Oscar Benjamin wrote:
> On 5 January 2013 16:01, Chris Angelico wrote:
>
> > On Sun, Jan 6, 2013 at 2:56 AM, Oscar Benjamin
>
> > wrote:
>
> >> On 4 January 2013 15:53, Grant Edwards wrote:
>
> >>> On 2013-01-04, Steven D'Aprano
> >>> wrote:
>
> On Thu, 03 Jan 2013 23:25:51 +, Grant Edwards wrote:
>
>
>
> * But frankly, you should avoid eval, and write your own mini-integer
>
> arithmetic evaluator which avoids even the most remote possibility
>
> of exploit.
>
> >>>
>
> >>> That's obviously the "right" thing to do. I suppose I should figure
>
> >>> out how to use the ast module.
>
> >>
>
> >> Someone has already created a module that does this called numexpr. Is
>
> >> there some reason why you don't want to use that?
>
> >>
>
> > import numexpr
>
> > numexpr.evaluate('2+4*5')
>
> >> array(22, dtype=int32)
>
> > numexpr.evaluate('2+a*5', {'a':4})
>
> >> array(22L)
>
> >
>
> > Is that from PyPI? It's not in my Python 3.3 installation. Obvious
>
> > reason not to use it: Unaware of it. :)
>
>
>
> My apologies. I should have at least provided a link:
>
> http://code.google.com/p/numexpr/
>
>
>
> I installed it from the ubuntu repo under the name python-numexpr. It
>
> is also on PyPI:
>
> http://pypi.python.org/pypi/numexpr
>
>
>
> numexpr is a well established project intended primarily for memory
>
> and cache efficient computations over large arrays of data. Possibly
>
> as a side effect, it can also be used to evaluate simple algebraic
>
> expressions involving ordinary scalar variables.
>
>
>
>
>
> Oscar
The asteval module http://pypi.python.org/pypi/asteval/0.9 and
http://newville.github.com/asteval/ might be another alternative. It's not as
fast as numexpr, but a bit more general. It uses the ast module to "compile" an
expression into the AST, then walks through that, intercepting Name nodes and
using a flat namespace of variables. It disallows imports and does not support
all python constructs, but it is a fairly complete in supporting python syntax.
It makes no claim at actually being safe from malicious attack, but should be
safer than a straight eval(), and prevent accidental problems when evaluating
user-input as code. If anyone can find exploits within it, I'd be happy to try
to fix them.
--Matt
--
http://mail.python.org/mailman/listinfo/python-list
Re: Yet another attempt at a safe eval() call
On 5 January 2013 16:01, Chris Angelico wrote:
> On Sun, Jan 6, 2013 at 2:56 AM, Oscar Benjamin
> wrote:
>> On 4 January 2013 15:53, Grant Edwards wrote:
>>> On 2013-01-04, Steven D'Aprano wrote:
On Thu, 03 Jan 2013 23:25:51 +, Grant Edwards wrote:
* But frankly, you should avoid eval, and write your own mini-integer
arithmetic evaluator which avoids even the most remote possibility
of exploit.
>>>
>>> That's obviously the "right" thing to do. I suppose I should figure
>>> out how to use the ast module.
>>
>> Someone has already created a module that does this called numexpr. Is
>> there some reason why you don't want to use that?
>>
> import numexpr
> numexpr.evaluate('2+4*5')
>> array(22, dtype=int32)
> numexpr.evaluate('2+a*5', {'a':4})
>> array(22L)
>
> Is that from PyPI? It's not in my Python 3.3 installation. Obvious
> reason not to use it: Unaware of it. :)
My apologies. I should have at least provided a link:
http://code.google.com/p/numexpr/
I installed it from the ubuntu repo under the name python-numexpr. It
is also on PyPI:
http://pypi.python.org/pypi/numexpr
numexpr is a well established project intended primarily for memory
and cache efficient computations over large arrays of data. Possibly
as a side effect, it can also be used to evaluate simple algebraic
expressions involving ordinary scalar variables.
Oscar
--
http://mail.python.org/mailman/listinfo/python-list
Re: Random List Loop?!
On 5 January 2013 15:47, Christian Gabriel wrote: > Hi > > I have tried now for ages to make a loop that does the following: > > Makes a new list with 9 random values, from 9 different lists, with 9 > elements. > > And makes sure that none of the elements repeat! > > Is there anyone that can help, with a very simple solution?? I'm sure that there is a simple solution but I don't fully understand your problem could you perhaps provide an example with actual numbers (perhaps use 3 instead of 9 so it's easier to follow)? In any case I suspect that you want something involving range() and random.shuffle() if that helps. Oscar -- http://mail.python.org/mailman/listinfo/python-list
Re: Random List Loop?!
On Sun, Jan 6, 2013 at 2:47 AM, Christian Gabriel wrote: > Hi > > I have tried now for ages to make a loop that does the following: > > Makes a new list with 9 random values, from 9 different lists, with 9 > elements. > > And makes sure that none of the elements repeat! > > Is there anyone that can help, with a very simple solution?? Sounds like a homework question to me. You've tried. What code have you come up with, and to what extent does it fall short of your goal? The nine different lists - do they have unique elements? Are you able to use sets? (If you haven't been taught what a set is, the answer's probably no.) ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Yet another attempt at a safe eval() call
On Sun, Jan 6, 2013 at 2:56 AM, Oscar Benjamin
wrote:
> On 4 January 2013 15:53, Grant Edwards wrote:
>> On 2013-01-04, Steven D'Aprano wrote:
>>> On Thu, 03 Jan 2013 23:25:51 +, Grant Edwards wrote:
>>>
>>> * But frankly, you should avoid eval, and write your own mini-integer
>>> arithmetic evaluator which avoids even the most remote possibility
>>> of exploit.
>>
>> That's obviously the "right" thing to do. I suppose I should figure
>> out how to use the ast module.
>
> Someone has already created a module that does this called numexpr. Is
> there some reason why you don't want to use that?
>
import numexpr
numexpr.evaluate('2+4*5')
> array(22, dtype=int32)
numexpr.evaluate('2+a*5', {'a':4})
> array(22L)
Is that from PyPI? It's not in my Python 3.3 installation. Obvious
reason not to use it: Unaware of it. :)
ChrisA
--
http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On Sun, Jan 6, 2013 at 2:38 AM, Roy Smith wrote: > In article , > Chris Angelico wrote: > >> it may or may not run faster than the explicit state machine, > > You got me by a factor of 3 or 4. Not bad. You miss my point, though. I went for simple Pythonic code, and never measured its performance, on the expectation that it's "good enough". Written in C, the state machine is probably WAY faster than splitting and then iterating. My C++ MUD client uses code similar to that to parse TELNET and ANSI codes from a stream of bytes in a socket (and one of its "states" is that there's no more data available, so wait on the socket); the rewrite in a high level language divides the string on "\xFF" for TELNET and "\x1B" for ANSI, working them separately, and then afterward splits on "\n" to divide into lines. The code's much less convoluted, it's easier to test different parts (because I can simply call the ANSI parser with a block of text), and on a modern computer, you can't see the performance difference (since you spend most of your time waiting for socket data anyway). But it's gratifying to know that the obvious and brief way to do things is fast too :) >> but IMHO it's a lot clearer to read a split() than something >> that changes state when a particular character is found. > > Maybe. But being familiar with state machines is still a handy skill. > DNA sequence analysis has lots of problems like "find a start codon > which is within about 50 bases of a binding site, and then copy > everything up until you find a stop codon". Things like that often map > well to state machines. Especially if you're trying to do it in > parallel in all three reading frames. Sure. And if you're working with petabytes of data, these considerations become fairly important. When that happens, you start rewriting your algorithms in C, or using Cython, or something; at very least, you start rewriting clear and simple algorithms into more complex ones. But all this happens *after* the code has been tested and proven. All the rewrites can be verified as being identical to their reference implementations; you can test one piece at a time as you change them. It's ever so much easier to work that way. At work, we had one employee whose code was, shall we say, less than stellar. At one point, he embarked on a months-long rewrite of one of his modules; meanwhile, I was unable to adequately test code that called on it. Once the rewrite was finally complete, I discovered myriad bugs in my own code, ones that would have been found and fixed instantly if I'd had even a slow version of the code to work against. Starting with something you can easily debug helps enormously with that, because debugging doesn't demand mega-TPS throughput. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Random List Loop?!
In article , Christian Gabriel wrote: > Hi > > I have tried now for ages to make a loop that does the following: > > Makes a new list with 9 random values, from 9 different lists, with 9 > elements. > > And makes sure that none of the elements repeat! > > Is there anyone that can help, with a very simple solution?? > > Best > > Christian You want random.sample() http://docs.python.org/2/library/random.html#random.sample -- http://mail.python.org/mailman/listinfo/python-list
Re: Yet another attempt at a safe eval() call
On 4 January 2013 15:53, Grant Edwards wrote:
> On 2013-01-04, Steven D'Aprano wrote:
>> On Thu, 03 Jan 2013 23:25:51 +, Grant Edwards wrote:
>>
>> * But frankly, you should avoid eval, and write your own mini-integer
>> arithmetic evaluator which avoids even the most remote possibility
>> of exploit.
>
> That's obviously the "right" thing to do. I suppose I should figure
> out how to use the ast module.
Someone has already created a module that does this called numexpr. Is
there some reason why you don't want to use that?
>>> import numexpr
>>> numexpr.evaluate('2+4*5')
array(22, dtype=int32)
>>> numexpr.evaluate('2+a*5', {'a':4})
array(22L)
Oscar
--
http://mail.python.org/mailman/listinfo/python-list
Random List Loop?!
Hi I have tried now for ages to make a loop that does the following: Makes a new list with 9 random values, from 9 different lists, with 9 elements. And makes sure that none of the elements repeat! Is there anyone that can help, with a very simple solution?? Best Christian -- http://mail.python.org/mailman/listinfo/python-list
Re: Couting the number of lines of code of a python program
In article ,
Dave Angel wrote:
> On 01/05/2013 10:17 AM, chaouche yacine wrote:
> >
>
>
> >
> > Here is my implementation :
> >
> > defcount_loc(lines):nb_lines =0docstring =Falseforline inlines:line
> > =line.strip()ifline ==""\ orline.startswith("#")\ ordocstring
> > andnot(line.startswith('"""')orline.startswith("'''"))\
> > or(line.startswith("'''")andline.endswith("'''")andlen(line)>3)\
> > or(line.startswith('"""')andline.endswith('"""')andlen(line)>3):continue#
> > this is either a starting or ending
> > docstringelifline.startswith('"""')orline.startswith("'''"):docstring
> > =notdocstring continueelse:nb_lines +=1returnnb_lines
>
> Wow, this is thoroughly garbled. Please configure your email (yahoo?)
> to use text mode email, to not delete spaces, to honor newlines, etc.
Nice to know that wasn't just another case of my using an antiquated
news reader :-)
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Re: Couting the number of lines of code of a python program
Sorry, I don't know what went wrong, here is another paste (hopefully this will
work this time). If you prefer, this a link anchor to the function
https://www.assembla.com/code/tahar/subversion/nodes/tahar.py?rev=8#ln340
def count_loc(lines):
nb_lines = 0
docstring = False
for line in lines:
line = line.strip()
if line == "" \
or line.startswith("#") \
or docstring and not (line.startswith('"""') or
line.startswith("'''"))\
or (line.startswith("'''") and line.endswith("'''") and len(line)
>3) \
or (line.startswith('"""') and line.endswith('"""') and len(line)
>3) :
continue
# this is either a starting or ending docstring
elif line.startswith('"""') or line.startswith("'''"):
docstring = not docstring
continue
else:
nb_lines += 1
return nb_lines
- Original Message -
From: Chris Angelico
To: python-list@python.org
Cc:
Sent: Saturday, January 5, 2013 4:25 PM
Subject: Re: Couting the number of lines of code of a python program
On Sun, Jan 6, 2013 at 2:17 AM, chaouche yacine
wrote:
> defcount_loc(lines):nb_lines =0docstring =Falseforline inlines:line
> =line.strip()ifline ==""\ orline.startswith("#")\ ordocstring
> andnot(line.startswith('"""')orline.startswith("'''"))\
> or(line.startswith("'''")andline.endswith("'''")andlen(line)>3)\
> or(line.startswith('"""')andline.endswith('"""')andlen(line)>3):continue#
> this is either a starting or ending
> docstringelifline.startswith('"""')orline.startswith("'''"):docstring
> =notdocstring continueelse:nb_lines +=1returnnb_lines
Ow-what? Something's gone wrong with all your whitespace, I think...
can you paste again please?
ChrisA
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Re: Need a specific sort of string modification. Can someone help?
In article , Chris Angelico wrote: > it may or may not run faster than the explicit state machine, Hmmm, hard to say. Both are O(n), but yours makes several more copies of the data than mine (the string addition, the replace(), the split(), the string slicing). We both make copies as we put fragments into a list, and when we do the join(). On the other hand, yours does all that inside the library, which is generally faster than random python code. Let's see: My way: real0m2.097s user0m2.078s sys 0m0.016s Your way: real0m0.649s user0m0.622s sys 0m0.025s You got me by a factor of 3 or 4. Not bad. And not terribly surprising. Once you've got things to the same O() group, pushing as much data manipulation as you can down into the library is usually a pretty effective optimization technique. > but IMHO it's a lot clearer to read a split() than something > that changes state when a particular character is found. Maybe. But being familiar with state machines is still a handy skill. DNA sequence analysis has lots of problems like "find a start codon which is within about 50 bases of a binding site, and then copy everything up until you find a stop codon". Things like that often map well to state machines. Especially if you're trying to do it in parallel in all three reading frames. -- http://mail.python.org/mailman/listinfo/python-list
Re: Couting the number of lines of code of a python program
On 01/05/2013 10:17 AM, chaouche yacine wrote:
>
>
> Here is my implementation :
>
> defcount_loc(lines):nb_lines =0docstring =Falseforline inlines:line
> =line.strip()ifline ==""\ orline.startswith("#")\ ordocstring
> andnot(line.startswith('"""')orline.startswith("'''"))\
> or(line.startswith("'''")andline.endswith("'''")andlen(line)>3)\
> or(line.startswith('"""')andline.endswith('"""')andlen(line)>3):continue#
> this is either a starting or ending
> docstringelifline.startswith('"""')orline.startswith("'''"):docstring
> =notdocstring continueelse:nb_lines +=1returnnb_lines
Wow, this is thoroughly garbled. Please configure your email (yahoo?)
to use text mode email, to not delete spaces, to honor newlines, etc.
>
>
> - Original Message -
> From: Chris Angelico
> To: python-list@python.org
Why is the quoted part *after* your message? Please don't top-post on
this list (or most of them). It gets too garbled after one or two
generations.
--
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--
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Re: Couting the number of lines of code of a python program
On Sun, Jan 6, 2013 at 2:17 AM, chaouche yacine
wrote:
> defcount_loc(lines):nb_lines =0docstring =Falseforline inlines:line
> =line.strip()ifline ==""\ orline.startswith("#")\ ordocstring
> andnot(line.startswith('"""')orline.startswith("'''"))\
> or(line.startswith("'''")andline.endswith("'''")andlen(line)>3)\
> or(line.startswith('"""')andline.endswith('"""')andlen(line)>3):continue#
> this is either a starting or ending
> docstringelifline.startswith('"""')orline.startswith("'''"):docstring
> =notdocstring continueelse:nb_lines +=1returnnb_lines
Ow-what? Something's gone wrong with all your whitespace, I think...
can you paste again please?
ChrisA
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Re: Couting the number of lines of code of a python program
The idea started off as a volumetric information of my projects, but evolved to
a sort of code browser that would display classes, methods and functions in a
tree-like structure, and now I mostly want to use it with other people's code
as a way to have the big picture. So I would say that it is used both for my
programs (to get a feeling of their size) as much as it is used for others'
code.
> But counting lines of code is a hairy thing to do. Do blank lines,
> comments, and multi-line strings count?
The way I implmented it, they do not, particulary docstrings (even though it
seems that many people think docstrings are actual code). My opinion on
docstrings is that they're not instructions. I want to know how many lines of
instructions a program has. Comments, blank lines and docstrings are not
intructions.
Here is my implementation :
defcount_loc(lines):nb_lines =0docstring =Falseforline inlines:line
=line.strip()ifline ==""\ orline.startswith("#")\ ordocstring
andnot(line.startswith('"""')orline.startswith("'''"))\
or(line.startswith("'''")andline.endswith("'''")andlen(line)>3)\
or(line.startswith('"""')andline.endswith('"""')andlen(line)>3):continue# this
is either a starting or ending
docstringelifline.startswith('"""')orline.startswith("'''"):docstring
=notdocstring continueelse:nb_lines +=1returnnb_lines
- Original Message -
From: Chris Angelico
To: python-list@python.org
Cc:
Sent: Saturday, January 5, 2013 3:09 PM
Subject: Re: Couting the number of lines of code of a python program
On Sun, Jan 6, 2013 at 12:55 AM, chaouche yacine
wrote:
> The
> problem is that I'm using the inspect module, because it provides a
> nice function inspect.getsourcelines that takes a python object and
> return its number of lines of code. BUT, it works on live objects, that
> means one has to first import the module he wants to process, and this
> can have side effects (example : GUI programs).
If you're using this entirely on your own code, one good way to solve
the problem is to make your code always importable. Protect your
top-level code with "if __name__=='__main__':" (and possibly put it
into a function main() if that simplifies your code counting), and you
should then be able to import it as-is, and all you'll do is define ams and
bunch of functions/classes.
But counting lines of code is a hairy thing to do. Do blank lines,
comments, and multi-line strings count?
ChrisA
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Re: Need a specific sort of string modification. Can someone help?
On Sun, Jan 6, 2013 at 2:03 AM, Roy Smith wrote: > That's why I chose to split this where I did. It was where the scan > direction changed. Ah, good point. In any case, this is a fairly simple and clear way of doing things; it may or may not run faster than the explicit state machine, but IMHO it's a lot clearer to read a split() than something that changes state when a particular character is found. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
In article ,
Chris Angelico wrote:
> On Sun, Jan 6, 2013 at 1:30 AM, Roy Smith wrote:
> > In article ,
> > Chris Angelico wrote:
> >
> >> result = "".join([x[int(x[0])+1:] for x in
> >> ("0"+s).replace("-","+").split("+")])
> >
> > That's exceedingly clever. But bordering on line noise. At the very
> > least, I would break it up into a couple of lines to make it easier to
> > understand (plus you can print out the intermediate values to see what's
> > going on):
> >
> > chunks = ("0"+s).replace("-","+").split("+")
> > result = "".join([x[int(x[0])+1:] for x in chunks]
>
> Sure. You can always split a one-liner to taste, doesn't much matter
> where.
Well, there are better and worse places to split things. Consider these
three statements:
result = f1().f2().f3().f4().f5()
result = f1(f2.f3(f4().f5()))
result = f1(f2(3(f4(f5()
Same number of function calls, but the middle one is clearly the most
difficult to understand. The reason is because the scan direction keeps
changing. The first one is strictly left-to-right. The last one is
strictly inside-to-outside. The middle one is all over the place.
That's why I chose to split this where I did. It was where the scan
direction changed.
Readability matters.
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Re: Need a specific sort of string modification. Can someone help?
On Sun, Jan 6, 2013 at 1:30 AM, Roy Smith wrote:
> In article ,
> Chris Angelico wrote:
>
>> result = "".join([x[int(x[0])+1:] for x in
>> ("0"+s).replace("-","+").split("+")])
>
> That's exceedingly clever. But bordering on line noise. At the very
> least, I would break it up into a couple of lines to make it easier to
> understand (plus you can print out the intermediate values to see what's
> going on):
>
> chunks = ("0"+s).replace("-","+").split("+")
> result = "".join([x[int(x[0])+1:] for x in chunks]
Sure. You can always split a one-liner to taste, doesn't much matter
where. You could split it majorly into half a dozen lines if you want,
doesn't make a lot of diff. It'll work the same way :)
ChrisA
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Re: Windows Installer Error
On Saturday, January 5, 2013 8:30:39 AM UTC-6, matt...@gmail.com wrote: > I am running on Windows 7 Professional x64 with latest service pack and I > cannot get Python to install. I run the python-3.2.1.msi, and after I select > the installation directory, I get a popup that says "There is a problem with > this Windows Installer package. A DLL required for this install to complete > could not be run. Contact your support personnel or package vendor". 2.7.3, > amd64, and older packages all do the exact same thing. NVM, I solved it just this very moment. I found this topic http://superuser.com/questions/478631/dll-could-not-be-run-for-msi-installers. It turns out I had to go to my Temp directory and give Full Control to the Everyone group. No idea why the MSI wouldn't have admin rights. -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
In article ,
Chris Angelico wrote:
> result = "".join([x[int(x[0])+1:] for x in
> ("0"+s).replace("-","+").split("+")])
That's exceedingly clever. But bordering on line noise. At the very
least, I would break it up into a couple of lines to make it easier to
understand (plus you can print out the intermediate values to see what's
going on):
chunks = ("0"+s).replace("-","+").split("+")
result = "".join([x[int(x[0])+1:] for x in chunks]
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Windows Installer Error
I am running on Windows 7 Professional x64 with latest service pack and I cannot get Python to install. I run the python-3.2.1.msi, and after I select the installation directory, I get a popup that says "There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor". 2.7.3, amd64, and older packages all do the exact same thing. -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
In article , Sia wrote: > I have strings such as: > > tA.-2AG.-2AG,-2ag > or > .+3ACG.+5CAACG.+3ACG.+3ACG Some kind of DNA binding site? A couple of questions. Are the numbers always single digits? How much data is there? Are we talking a few hundred 20-character strings, or all of Genbank? > The plus and minus signs are always followed by a number (say, i). I want > python to find each single plus or minus, remove the sign, the number after > it and remove i characters after that. So the two strings above become: > > tA.., > and > ... If I follow your description properly, the last output should be "" (4 dots), right? This looks like it should work. I'm sure there's more efficient ways to do it, but for small inputs, this should be ok. The general pattern here is a state machine. It's a good pattern to learn if you're going to be doing any kind of sequence analysis. See, for example, http://en.wikipedia.org/wiki/State_machine. # Build up the new string as a list (for efficiency) new = [] # Keep track of what state we're in. The three possible states # are 1) scanning for a region to be deleted, 2) looking for the # number, and 3) reading past the letters to be deleted. SCANNING = 1 NUMBER = 2 DROPPING = 3 state = SCANNING # If we are in state DROPPING, dropcount is the number of # letters remaining to be dropped. dropcount = 0 old = '.+3ACG.+5CAACG.+3ACG.+3ACG' for c in old: if state == SCANNING: if c in '+-': state = NUMBER else: new.append(c) elif state == NUMBER: # Assume the counts are all single digits. If not, then # we'll need a 4th state for accumulating the digits. dropcount = int(c) state = DROPPING else: assert state == DROPPING dropcount -= 1 if dropcount == 0: state = SCANNING print ''.join(new) -- http://mail.python.org/mailman/listinfo/python-list
Re: Couting the number of lines of code of a python program
On Sun, Jan 6, 2013 at 12:55 AM, chaouche yacine wrote: > The > problem is that I'm using the inspect module, because it provides a > nice function inspect.getsourcelines that takes a python object and > return its number of lines of code. BUT, it works on live objects, that > means one has to first import the module he wants to process, and this > can have side effects (example : GUI programs). If you're using this entirely on your own code, one good way to solve the problem is to make your code always importable. Protect your top-level code with "if __name__=='__main__':" (and possibly put it into a function main() if that simplifies your code counting), and you should then be able to import it as-is, and all you'll do is define a bunch of functions/classes. But counting lines of code is a hairy thing to do. Do blank lines, comments, and multi-line strings count? ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Couting the number of lines of code of a python program
Hello. I'v written a small script that prints the number of lines of code of a python program to stdout (by module, function, class and method), the sources are available online here https://www.assembla.com/code/tahar/subversion/nodes. The readme has an example usage as well as a trace of what the script prints. The problem is that I'm using the inspect module, because it provides a nice function inspect.getsourcelines that takes a python object and return its number of lines of code. BUT, it works on live objects, that means one has to first import the module he wants to process, and this can have side effects (example : GUI programs). So my question is how can one count the number of lines of code of a python program without importing it (static code analysis) ? Some people on IRC advised me to look for the AST module. Can you give me a little help on how to use this module to count the number of lines of code of a function/method ? Thanks in advance for your help. -- http://mail.python.org/mailman/listinfo/python-list
Re: PyGreSQL 4.1 released
On Sat, 5 Jan 2013 13:23:55 +0100 Michael Poeltl wrote: > no python3 support yet? > can you tell us when pygresql will be ready for python3? Hard to say when (we all have day jobs) but it is planned for version 5.0. You can track our milestones at http://trac.vex.net:8000/pgtracker We will probably get version 4.2 released shortly and then branch 5.x and start working on Python 3 support. -- D'Arcy J.M. Cain PyGreSQL Development Group http://www.PyGreSQL.org IM:da...@vex.net -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with exam task for college
On Sun, Jan 6, 2013 at 12:14 AM, wrote: > that's probably it, how do i solve it? I'm afraid I can't help you there. Check out the docs for the getkey function and see if it can be put into non-blocking mode; if not, you may have to completely change your model. For instance, if I were writing this sort of game today, I'd probably use a GUI system that fires an event whenever a key is pressed/released, and then have a timer-tick for the descent, rather than explicit sleep() calls. But it depends on your UI facilities. The LANDER.BAS that I played with - yes, it was written in BASIC - was fully prompt-driven. To move to the next time unit, you had to answer all its prompts. Advantage: No need to code a Pause feature. Disadvantage: The game ended up way too scientific, like D&D combat. (It's amazing how your party of bumbling characters suddenly become lightning-fast strategists as soon as initiative is rolled!) ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame - importing GL - very bad...
On Sun, Jan 6, 2013 at 12:06 AM, someone wrote: > On 01/05/2013 12:47 PM, Chris Angelico wrote: >> You can find good references on the subject in various >> places, but call-by-reference as implemented in Pascal simply doesn't >> exist in most modern languages, because its semantics are way >> confusing. The name given to this technique varies; here's a couple of >> links: >> >> http://effbot.org/zone/call-by-object.htm >> http://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_sharing > > If you don't like calling it "pass-by-reference", perhaps you prefer calling > it: “call by object reference“... From: > http://effbot.org/zone/call-by-object.htm > > In any case I think we understand each other. That's one of the links I just posted :) It's not just a naming difference, though. With Pascal's pass-by-reference semantics, this code would act differently: def foo(x): x = 5 a = 2 foo(a) print(a) Python prints 2, because the assignment to x just rebinds the name inside foo. True pass-by-reference actually changes the caller's variable. C can achieve this by means of pointers; in Python, you can pass and mutate a list, thus: def foo(x): x[0] = 5 # Dereference the pointer, kinda x=[None] # Declare a pointer variable, ish x[0] = 2 foo(x) # Don't forget to drop the [0] when passing the pointer to another function print(x[0]) # Prints 5. See? We have pass-by-reference! But otherwise, rebinding names in the function has no effect on anything outside. Among other things, this guarantees that, in any situation, a name referencing an object can be perfectly substituted for any other name referencing the same object, or any other way of accessing the object. def foo(lst): lst[0]=len(lst) x = [10,20,30] y = x foo(x) # These two... foo(y) # ... are identical! This is a philosophy that extends through the rest of the language. A function returning a list can be directly dereferenced, as can a list literal: def foo(): return [0,1,4,9,16] print( ["Hello","world!","Testing","Testing","One","Two","Three"][foo()[2]] ) This is a flexibility and power that just doesn't exist in many older languages (C and PHP, I'm looking at you). Object semantics make more sense than any other system for a modern high level language, which is why many of them do things that way. ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with exam task for college
that's probably it, how do i solve it? -- http://mail.python.org/mailman/listinfo/python-list
Re: pylint, was Re: pygame - importing GL - very bad...
On 01/05/2013 01:49 PM, Jan Riechers wrote:
On 05.01.2013 03:11, someone wrote:
But about the regular expressions (a bit deeper look into that):
Like said of Chris:
[a-z]
defines a "catching group", in this case all ascii lowercase letters
ranging from "a" to "z". If noting else is provided, the rule matches
one letter if there is no range defined by something like:
{} -> Target a range of a match/hit
There are also a
? -> Lazy match
* -> Gready match
[A-Z][0-9]{1,3} means translated:
Look for any uppercase letter in ascii(!) (not "öäü" or similiar)
ranging from "A" to "Z".
Now look for any digit (2nd catching group) with the addition to satisfy
the rule ONLY if there are at least 1 to 3 digits found.
Note: If there are 4 or more digits - the catching rule is still
satisfied and will provide a match/hit.
Ok, thanks a lot for the elaboration... I think I need to work with it
myself at some time to be sure of understanding it...
If there is a follow up group, the next evaluation is gone through if
present and so forth. If the expression is satisfied, the match is
returned.
The lazy "?" and greedy "*" matches try to satisfy, as the naming
implies, to match as less or as much of what you have asked for.
For example the regular expression is valid:
0* -> Look for a zero, and be greedy as of how many zeros you want match
which might follow.
Regular expressions don't have to include catching groups in order to work.
But when you use them yourself somehow, its quite simple I think.
I guess you are anyhow busy mangling with pyLint, PEP-Standards and
pyOpenGL - so good luck with that :)
You're right - I'm a bit "overbooked" at the moment - but thanks a lot
for clarifyring this with the regexps :-)
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Re: pygame - importing GL - very bad...
On 01/05/2013 12:47 PM, Chris Angelico wrote: C has typed variables, so it's a compile-time error to try to put any other type into that variable. Python doesn't. That flexibility comes at the cost of error-catching. There are hybrid systems, but in general, type declarations imply variable declarations, and that's something that Python doesn't want. (I'm of the opinion that declarations aren't such a bad thing; they make some aspects of scoping easier. However, that's a design decision that Python is as unlikely to reverse as indentation-defined blocks.) Understood. Ok, I'll look forward to that. Recently I had some problems with pass-by-value vs pass-by-reference. I googled the problem and found that by default python passes by reference. No, it doesn't. You can find good references on the subject in various places, but call-by-reference as implemented in Pascal simply doesn't exist in most modern languages, because its semantics are way confusing. The name given to this technique varies; here's a couple of links: http://effbot.org/zone/call-by-object.htm http://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_sharing If you don't like calling it "pass-by-reference", perhaps you prefer calling it: “call by object reference“... From: http://effbot.org/zone/call-by-object.htm In any case I think we understand each other. -- http://mail.python.org/mailman/listinfo/python-list
Re: pylint, was Re: pygame - importing GL - very bad...
On 05.01.2013 03:11, someone wrote:
On 01/03/2013 12:27 PM, Chris Angelico wrote:
On Thu, Jan 3, 2013 at 10:19 PM, someone wrote:
Doesn't this "[ ... ]" mean something optional?
What does {2,30}$ mean?
I think $ means that the {2,30} is something in the end of the
sentence...
You can find regular expression primers all over the internet, but to
answer these specific questions: [...] means any of the characters in
the range; the $ means "end of string"; and {2,30} means at least two,
and at most thirty, of the preceding character. So you have to have
one from the first group, then 2-30 from the second, for a total of
3-31 characters in your names.
Got it, thanks!
Just following the discussion which is very interesting, even so when
not working with OpenGL (which looks like a nightmare with that naming
space) :)
But about the regular expressions (a bit deeper look into that):
Like said of Chris:
[a-z]
defines a "catching group", in this case all ascii lowercase letters
ranging from "a" to "z". If noting else is provided, the rule matches
one letter if there is no range defined by something like:
{} -> Target a range of a match/hit
There are also a
? -> Lazy match
* -> Gready match
[A-Z][0-9]{1,3} means translated:
Look for any uppercase letter in ascii(!) (not "öäü" or similiar)
ranging from "A" to "Z".
Now look for any digit (2nd catching group) with the addition to satisfy
the rule ONLY if there are at least 1 to 3 digits found.
Note: If there are 4 or more digits - the catching rule is still
satisfied and will provide a match/hit.
If there is a follow up group, the next evaluation is gone through if
present and so forth. If the expression is satisfied, the match is returned.
The lazy "?" and greedy "*" matches try to satisfy, as the naming
implies, to match as less or as much of what you have asked for.
For example the regular expression is valid:
0* -> Look for a zero, and be greedy as of how many zeros you want match
which might follow.
Regular expressions don't have to include catching groups in order to work.
But when you use them yourself somehow, its quite simple I think.
I guess you are anyhow busy mangling with pyLint, PEP-Standards and
pyOpenGL - so good luck with that :)
Jan Riechers
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Re: problem with exam task for college
On Sat, Jan 5, 2013 at 11:24 PM, wrote: > hy again,thanx, i updated my code with your more efficient approach :), so > that possibly resolves problem number 2, but still leaves me with problem > n°1, my code is still stuck in the first update of the fuel tank > (brandstoftank), for the sake of your easyness i'll paste the code again Not sure what you mean by "stuck", but is it that scene.kb.getkey() waits for a key? ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: PyGreSQL 4.1 released
no python3 support yet? can you tell us when pygresql will be ready for python3? thx Michael * D'Arcy J.M. Cain [2013-01-03 15:05]: > --- > Release of PyGreSQL version 4.1 > --- > > It has been a long time coming but PyGreSQL v4.1 has been released. > > It is available at: http://pygresql.org/files/PyGreSQL-4.1.tgz. > > If you are running NetBSD, look in the packages directory under > databases. There is also a package in the FreeBSD ports collection > which will probably be updated shortly. > > Please refer to `changelog.txt `_ > for things that have changed in this version. > > Please refer to `readme.txt `_ > for general information. > > This version has been built and unit tested on: > - NetBSD > - FreeBSD > - openSUSE 12.2 > - Windows 7 with both MinGW and Visual Studio > - PostgreSQL 8.4, 9.0 and 9.2 32 and 64bit > - Python 2.5, 2.6 and 2.7 32 and 64bit > > -- > D'Arcy J.M. Cain > PyGreSQL Development Group > http://www.PyGreSQL.org IM:da...@vex.net > -- > http://mail.python.org/mailman/listinfo/python-list -- Michael Poeltl Computational Materials Physics voice: +43-1-4277-51409 Univ. Wien, Sensengasse 8/12 fax: +43-1-4277-9514 (or 9513) A-1090 Wien, AUSTRIA cmp.mpi.univie.ac.at --- slackware-13.37 | vim-7.3 | python-3.2.3 | mutt-1.5.21 | elinks-0.12 --- -- http://mail.python.org/mailman/listinfo/python-list
Re: problem with exam task for college
hy again,thanx, i updated my code with your more efficient approach :), so that possibly resolves problem number 2, but still leaves me with problem n°1, my code is still stuck in the first update of the fuel tank (brandstoftank), for the sake of your easyness i'll paste the code again from visual import * import time import math import random from datetime import datetime import operator class lunar_lander(object): def __init__(self): scene.title = 'mini star wars' scene.width = 375 scene.height = 550 scene.center = (0,0) self.pos = (0,0) self.axis = 0 self.brandstofmeter_view = brandstofmeter_view() self.ruimteschip = ruimteschip() self.view = game_view(self) def play(self): t=0 dt=0.01 while t<9: time.sleep(0.01) self.brandstofmeter_view.update() self.ruimteschip.update(dt) t = t + dt class game_view(object): def __init__(self,owner): autoscale=True box(pos=( 0, -375, 0), length=500, height=5, width=0, color = color.white) box(pos=(0,375, 0), length=500, height=5, width=0, color = color.white) box(pos=(-250,0, 0), length=5, height=750, width=0, color = color.white) box(pos=(250,0, 0), length=5, height=750, width=0, color = color.white) maan = curve(pos=[(-250,-353),(-240,-341),(-210,-354),(-199.5,-374)],color=color.red) maana = curve(pos=[(-199.5,-374),(-166,-374)],color=color.green) maanb = curve(pos=[(-166,-374),(-140,-357),(-80,-319),(-40,-361),(0,-321),(40,-329),(80,-347)],color=color.red) maanc = curve(pos=[(80,-347),(140,-347)],color=color.green) maand = curve(pos=[(140,-347),(162,-337),(189.5,-365),(210,-355),(240,-372),(250,-338)],color=color.red) for i in random.sample(range (-250,250),20): for j in random.sample(range (-375,375),20): sterren = points(pos = [i,j,0],size = 2, color=color.white) class brandstofmeter_view(object): def __init__(self): axis = 0 self.pos = (220,345) self.meter = box(pos = self.pos, lenght = 25, height = 45,color = color.green) def update (self): s = scene.kb.getkey() if (s == "up"): self.meter.height = self.meter.height - 1 class ruimteschip(object): def __init__(self): self.pos = vector(0,330) self.acceleration = vector(0,-88,0) self.axis = (1,0,0) self.hoek = (90*math.pi)/180 self.graden = math.degrees(self.hoek) self.gas = vector(10 * cos(self.hoek),10 * sin (self.hoek)) self.velocity = vector(0,0,0) self.angle = (1,0,0) self.view = ruimteschip_view(self) self.vlam = self.view.vlam self.frame = self.view.frame def update(self,dt): self.velocity = self.velocity + (self.acceleration * dt) self.pos = self.pos + self.velocity * dt a = 0 b = 0 if scene.kb.keys: a = a + 0.001 s = scene.kb.getkey() if (s == "up"): self.velocity = self.velocity + self.gas self.vlam.visible = True b = b + 2 if (s == "left"): self.gas = rotate(self.gas,angle = math.pi/10, axis = (0,0,1)) (x,y,z) = self.frame.axis self.frame.axis = (x,y,z-0.1) if (s == "right") : self.gas = rotate(self.gas,angle = -(math.pi/10), axis = (0,0,1)) (x,y,z) = self.frame.axis self.frame.axis = (x,y,z+0.1) if (a == 0): self.vlam.visible = False if self.pos.x > 250: self.pos.x = -250 if self.pos.x < -250: self.pos.x = 250 self.view.update(self) class ruimteschip_view(object): def __init__(self,owner): self.owner = owner self.frame = frame(pos = owner.pos,axis = owner.axis) self.motor = curve(frame = self.frame,pos=[(0,24.0),(22.0,24.0),(22.0,39.0),(-22.0,39.0),(-22,24),(0,24)]) self.capsule = curve(frame = self.frame,color = color.blue ,pos=[(0,39),(-3,39),(-9,44),(-12,46),(-18,48),(-22,50),(-18,52),(-12,54),(-9,56),(-3,61),(0,61),(3,59),(9,56),(12,54),(18,52),(22,50),(18,48),(12,46),(9,44),(3,39),(0,39)]) self.poota = curve(frame = self.frame,pos = [(-18,24),(-20,24),(-20,0),(-18,0),(-18,24)]) self.pootb = curve(frame = self.frame,pos = [(18,24),(20,24),(20,0),(18,0),(18,24)]) self.vlam = curve(frame = self.frame,color = color.orange , visible=false,pos = [(0,24.0),(-9.0,14.0),(0,-5.0),(9,14.0),(0,24.0)]) def update(self,owner): self.frame
Re: Evaluate postgres boolean field
Brilliant, thanks guys -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame - importing GL - very bad...
On Sat, Jan 5, 2013 at 9:49 PM, someone wrote: > Ok, I think you're right. At least I find that C-compilers catches many > errors/warnings which python don't say anything about. But also C require me > to define/declarer the types of variables before I use them... OTOH I guess > I like that python is faster to code in, compared to C... C has typed variables, so it's a compile-time error to try to put any other type into that variable. Python doesn't. That flexibility comes at the cost of error-catching. There are hybrid systems, but in general, type declarations imply variable declarations, and that's something that Python doesn't want. (I'm of the opinion that declarations aren't such a bad thing; they make some aspects of scoping easier. However, that's a design decision that Python is as unlikely to reverse as indentation-defined blocks.) > Ok, I'll look forward to that. Recently I had some problems with > pass-by-value vs pass-by-reference. I googled the problem and found that by > default python passes by reference. No, it doesn't. You can find good references on the subject in various places, but call-by-reference as implemented in Pascal simply doesn't exist in most modern languages, because its semantics are way confusing. The name given to this technique varies; here's a couple of links: http://effbot.org/zone/call-by-object.htm http://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_sharing ChrisA -- http://mail.python.org/mailman/listinfo/python-list
Re: New in Python , Need a Mentor
On 01/02/2013 05:30 PM, Chris Angelico wrote: On Thu, Jan 3, 2013 at 3:24 AM, Wolfgang Strobl wrote: Chris Angelico : I strongly recommend IDLE - much better editing/recall facilities than the command-line Python has), and work through the tutorial: Well, this is certainly a matter of taste. I'd recommend using some small, language independent programmers editor and some modern distributed version control system right at the beginning. Put your code, even the smallest snippets, under version control, make that a habit. Write small doctests for your code from the very beginning. Try to construct your code so that it works equally well as a module and as a standalone script Don't start developing web applications, write some small utilities for your own needs, first. Personally, I suggest SciTE and TortoiseHG on Windows, but that too is, as I said, a matter of taste. I don't edit code in IDLE, I just use it for interactive work. For actual script editing, agreed (though I use git rather than hg), but it really does help to have a way to *very* quickly test a line or two of code. I really REALLY like debugging with "eric"... http://eric-ide.python-projects.org/ -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame - importing GL - very bad...
On 01/05/2013 05:49 AM, someone wrote: > On 01/05/2013 02:30 AM, Dave Angel wrote: > >> >> Function objects are enormously useful, as you get more adept at using >> Python. > > Ok, I'll look forward to that. Recently I had some problems with > pass-by-value vs pass-by-reference. I googled the problem and found > that by default python passes by reference. Pascal has two calling conventions (value and reference). C always calls by value. C++ adds a call by reference, and maybe later C standards have added it as well. Python always calls by object. In fact, one could argue that there are no values (in the C sense) in Python. All names, and all attributes, and all slots in collections, are references to objects. So when you call a function, what you're doing is telling the function how to reference the same object(s). The usual way to say that is that the function call binds a new name to an existing object. If that object is mutable, then perhaps you wanted to do a copy first. Or perhaps you didn't. As you say, you debugged the program to find out. > I then debugged my program and finally found out that I should make a > copy (a new object) of the variable, before I passed it to my > function. And THIS solved my problem. But in C/C++ I think the default > is to pass by value, so this error in my program was a bit > unexpected... Anyway, I feel python is a great language for doing > things much faster than I could possibly do in C/C++. > > I also have on my todo-list to take my opengl-program and make it into > an executable. I mainly sit on a linux-pc but I want to distribute my > opengl program for windows (which has most users). I've found > something on google for py2app, cx_Freeze, bbfreeze and Freeze and I > hope this cross-platform thing does not cause too many problems... I > tried one of these tools a few weeks ago but I think I only succeeded > with a very simple hello-world program... Anyway, that's a problem > I'll investigate in a few months when I think/hope my opengl program > is finished... > -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
Re: pygame - importing GL - very bad...
On 01/05/2013 02:30 AM, Dave Angel wrote: from opengl import gl, glu, glut gl.rotate(...) gl.clear(gl.COLOR_BUFFER_BIT) Erhm, that's the same as above. Is that what you meant to write? No, it's not the same; here he did not capitalize the function names. Previously they look like class instantiations. Ah, you're right. Sorry :-) Well, I'm sometimes a bit annoyed that python doesn't give as many warnings/errors as one gets in C - for instance sometimes I copy/paste and forget to remove the trailing semi-colons. Trailing semi colons are legal in most cases. The semi-colon is a separator between statements, when one wants to put multiple statements on one line. However after I began to use pylint and friends, this error will be caught. Then sometimes I forgot to add () for function calls, which in C would cause an error by the compiler Actually no. In C, a function name without parentheses is also a function pointer. Not exactly the same as a function object, though C++ gets a lot closer. But the real reason C catches that typo is that the types most likely don't match, depending on what you meant to do with the return value. Ok, I think you're right. At least I find that C-compilers catches many errors/warnings which python don't say anything about. But also C require me to define/declarer the types of variables before I use them... OTOH I guess I like that python is faster to code in, compared to C... but which python allows so one can get the object (which maybe is also a good reason, but at least in the beginning when I learned python, this was very annoying + confusing to me). Function objects are enormously useful, as you get more adept at using Python. Ok, I'll look forward to that. Recently I had some problems with pass-by-value vs pass-by-reference. I googled the problem and found that by default python passes by reference. I then debugged my program and finally found out that I should make a copy (a new object) of the variable, before I passed it to my function. And THIS solved my problem. But in C/C++ I think the default is to pass by value, so this error in my program was a bit unexpected... Anyway, I feel python is a great language for doing things much faster than I could possibly do in C/C++. I also have on my todo-list to take my opengl-program and make it into an executable. I mainly sit on a linux-pc but I want to distribute my opengl program for windows (which has most users). I've found something on google for py2app, cx_Freeze, bbfreeze and Freeze and I hope this cross-platform thing does not cause too many problems... I tried one of these tools a few weeks ago but I think I only succeeded with a very simple hello-world program... Anyway, that's a problem I'll investigate in a few months when I think/hope my opengl program is finished... -- http://mail.python.org/mailman/listinfo/python-list
Re: Need a specific sort of string modification. Can someone help?
On Sat, Jan 5, 2013 at 7:35 PM, Sia wrote:
> I have strings such as:
>
> tA.-2AG.-2AG,-2ag
> or
> .+3ACG.+5CAACG.+3ACG.+3ACG
>
> The plus and minus signs are always followed by a number (say, i). I want
> python to find each single plus or minus, remove the sign, the number after
> it and remove i characters after that. So the two strings above become:
>
> tA..,
> and
> ...
>
> How can I do that?
Interesting. Are you guaranteed that there are no other plus or minus
signs? Is the number after the sign just one digit? Assuming the
answers to both are "yes", here's a one-liner:
s=".+3ACG.+5CAACG.+3ACG.+3ACG"
result = "".join([x[int(x[0])+1:] for x in ("0"+s).replace("-","+").split("+")])
Split on either - or +, then trim off that many characters from each
(that's the list comp), then join them back into a string.
ChrisA
--
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Re: Need a specific sort of string modification. Can someone help?
On 05/01/2013 10:35, Sia wrote:
I have strings such as:
tA.-2AG.-2AG,-2ag
or
.+3ACG.+5CAACG.+3ACG.+3ACG
The plus and minus signs are always followed by a number (say, i). I want
python to find each single plus or minus, remove the sign, the number after it
and remove i characters after that. So the two strings above become:
tA..,
and
...
How can I do that?
Thanks.
Here is a naive solution (I am sure there are more elegant ones) -
def strip(old_string):
new_string = ''
max = len(old_string)
pos = 0
while pos < max:
char = old_string[pos]
if char in ('-', '+'):
num_pos = pos+1
num_str = ''
while old_string[num_pos].isdigit():
num_str += old_string[num_pos]
num_pos += 1
pos = num_pos + int(num_str)
else:
new_string += old_string[pos]
pos += 1
return new_string
It caters for the possibility that the number following the +/- could be
greater than 9 - I don't know if you need that.
It works with your examples, except that the second one returns '',
which I think is correct - there are 4 dots in the original string.
HTH
Frank Millman
--
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Need a specific sort of string modification. Can someone help?
I have strings such as: tA.-2AG.-2AG,-2ag or .+3ACG.+5CAACG.+3ACG.+3ACG The plus and minus signs are always followed by a number (say, i). I want python to find each single plus or minus, remove the sign, the number after it and remove i characters after that. So the two strings above become: tA.., and ... How can I do that? Thanks. -- http://mail.python.org/mailman/listinfo/python-list
