Dynamically creating properties?
I have some XML, with a variable and somewhat unknown structure. I'd like to encapsulate this in a Python class and expose the text of the elements within as properties. How can I dynamically generate properties (or methods) and add them to my class? I can easily produce a dictionary of the required element names and their text values, but how do I create new properties at run time? Thanks, -- http://mail.python.org/mailman/listinfo/python-list
Re: SVN access with pysvn under Cygwin (Installation problems)
On 30 Jul, 20:30, Jason Tishler [EMAIL PROTECTED] wrote: You need to build (and install) pysvn under Cygwin. The pre-built Windows version will not work under Cygwin. Thanks. Presumably this same problem would affect anything that uses a .pyd under Cygwin? -- http://mail.python.org/mailman/listinfo/python-list
SVN access with pysvn under Cygwin (Installation problems)
I'm building Python tools to wrap up access to our Subversion / SVN source control system. It's to run on my desktop (Cygwin under Windows XP) and then later under Redhat. Trying to install the pysvn module I'm running into problems getting it to work under Cygwin. Works fine from a Windows command prompt, with both the svn_cmd.py example and my own Python code. Under Cygwin though I just get import failures. pysvn/__init__.py seems to be invoked happily enough, but then fails when it tries to import _pysvn_2_5.pyd $ python svn_cmd.py Traceback (most recent call last): File svn_cmd.py, line 10, in module import pysvn File /usr/lib/python2.5/pysvn/__init__.py, line 104, in module import _pysvn_2_5 ImportError: No module named _pysvn_2_5 Is there some trick to getting .pyd to work under Cygwin? I've tried the obvious twiddling with environment variables (and regedit), but I'm just guessing blindly. Thanks for any assistance. -- http://mail.python.org/mailman/listinfo/python-list
Using doctest with simple text files ?
I have a problem involving lots of simple text files (Java properties files), for which I'm building Python tools to manage their contents. I'm also writing lots of Python modules and using doctest to embed unit tests within them. Maintenance and shhared code ownership is an issue here. What's the best way to test my file modification operations, within the context of doctest-like testing? I like the simple immediacy of doctest and it's working well for my in-Python testing, but I can't seem to find a simple way of integrating it with the resultant text files (e.g. something like diff) Thanks -- http://mail.python.org/mailman/listinfo/python-list
Re: Fortran vs Python - Newbie Question
On 26 Mar, 14:20, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: what are the advantages of using Python for creating number crunching apps over Fortran?? If you have to ask, you've not experienced enough Fortran to know its sheer horror. You can write programs in Python that do usefully complicated things, and you can get them to work in a reasonable time. Fortran can't do this, for anything more than the trivial. Classic Fortran tasks of the past are now seen as trivial. OK, so they did it to a lot of data, but they really didn't do anything very complex to it. You can also write Python that other people can read and maintain. You can't do this in Fortran, without a truly insane amount of trouble. As Fortran programs have historically been authored and hacked on by successive generations of grad students, this is the most vital feature of all. Finally we're no longer so interested in number crunching. Number crunching used to consist of simple operations over vast arrays of data, although this was data with remarkably simple structure by today's standards. These just aren't the major class of problems of interest today. There's a massive difference between old-school FEA (bashing Newton and Hooke into tinier and tinier cells) and bioinformatics or anything involving the representation of big data graphs. Python is a tad slower than Fortran If the Fortran program turns out to have been broken all along, then who cares? -- http://mail.python.org/mailman/listinfo/python-list
Re: Help Required for Choosing Programming Language
On 16 Feb, 21:22, [EMAIL PROTECTED] wrote: I am VB6 programmer and wants to start new programming language Why? What is causing you to do this, and what do you need to achieve by doing it? i want to go through with GUI based programming language like VB.net GUI-based is fairly unimportant as it's just how you build your programs, not what they do afterwards. VB is GUI-based, Python can be GUI-based but is usually fairly text-based. What's probably more significant here is whether the resulting program runs in a GUI or not. VB obviously does, on the Windows desktop. Java also has a sizable market for cross-platform GUI applications. In many ways Java is more capable than VB, but also far less easy to work with for rapid simple applications (I'd take 10 year old VB over GridBag any time!). GUI programs are less important now than they were a few years ago, owing to the huge importance of the web and HTML. Although HTML can still be seen as GUI, it really needs to be worked with at the raw HTML source level (at least for quality work). This doesn't need any sort of GUI built into the language, so Python (or Ruby or Perl) are ideal. With the rise of AJAX toolkits, we're finally seeing HTML as a GUI turn into a workable choice for building sophisticated GUI apps in a sensible amount of time. Finally! The tools used here depend significantly on the toolkits used and it's still early days to pick winners. If I had to write Windows-only desktop GUI apps, then I'd stick with VB6 (which I wrote for years) or whatever M$oft decree to be its moral successor. Actually I'd probably stick with VB6 If I had to write cross-platform GUI desktop apps, then I'd be looking at whatever the favoured toolkit for Java is this week. Maybe Swing, if I wanted to get a paid job using it. Java Web Start needs looking at too. If I just had to make a sophisiticated GUI app appear on a lot of corporate desktops, then it would probably be based on Java Server Faces. For nearly all of the choices above, the language part of the task is minor in comparison to tiresome GUI building. That's just the way commerce works, and why we don't all get to write everything in Scheme or Haskell. If I had a free hand in writing better shell scripts, or in writing moderately complex algorithms with no visible UI, then I have chosen Python. It beats the hell out of Perl and is (AFAICS) better than Ruby. For building web reporting apps that generate HTML, then I'm also choosing to use my sparse Python knowledge rather than my substantial Java / JSP knowledge. Seems to be working so far. For web-hosted GUI apps, I don't know enough about Python to say. Doesn't look like it beats JSF though. There's also the question of what OOP means. For the mainstream languages, then classic statically-typed OO is done best by writing in Java. This has a cleaner OOP language design than C++, the benefit of a decade's hindsight and a clean slate. Dynamically or duck-typed languages like Python and Ruby are quite different from this. It's still OOP, but not how your uncle Bjarne knew it. Quite a culture shock too. -- http://mail.python.org/mailman/listinfo/python-list
Re: rot13 in a more Pythonic style?
On 14 Feb, 20:06, Beej [EMAIL PROTECTED] wrote: http://linuxgazette.net/109/pramode.html Thanks, that's a _really_ interesting link (Oh, I need to learn Scheme!) My code now looks like this, which I'm starting to feel much happier about in a functional sense. c_rot = lambda c, chars : (chr((ord(c) - ord(chars[0]) + (len(chars) // 2)) % len(chars) + ord(chars[0]))) c_rot13 = lambda c : (((c, \ c_rot(c, string.ascii_uppercase)) [c in string.ascii_uppercase]), \ c_rot(c, string.ascii_lowercase)) [c in string.ascii_lowercase] rot13 = lambda s : string.join([ c_rot13(c) for c in s ],'') I also considered this, but don't trust it as it relies on the two sets being mutually disjoint between their inputs and outputs. qc_rot = lambda c, chars : (c, c_rot(c, chars)) [c in chars] c_rot13 = lambda c : (qc_rot( qc_rot(c, string.ascii_lowercase), string.ascii_uppercase)) -- http://mail.python.org/mailman/listinfo/python-list
Re: rot13 in a more Pythonic style?
On 14 Feb, 21:59, Paul Rubin http://[EMAIL PROTECTED] wrote: Why don't you describe the actual problem instead of the rot13 analogy. I don't know what the actual problem is! I need to perform a complex mapping between old style structured identifiers and new style structured identifers. As the original specification was never thought through or written down anywhere, I'm now having to try and reverse- engineer from 5 years of collected inconsistent practice. So far I have about four pages of BNF to describe things and I'm still not sure what's accurate, what's inaccurate spec and what's merely an error in practice. Hopefully there's a neat little structure underlying it all and a few typos I can merely ignore, but probably it really is just an inconsistent structure that needs a lot of explicit tests around the corner-cases to make sense of. rot13 isn't the issue here, and I already know how to use .translate() What I'm after is a tutorial of my Python coding style for an example that's quite similar to the rot13 case. Your previous posting was very helpful here. -- http://mail.python.org/mailman/listinfo/python-list
Re: rot13 in a more Pythonic style?
On 15 Feb, 17:55, Dennis Lee Bieber [EMAIL PROTECTED] wrote: Sounds more like a case for a parser/lexer wherein the emitted code tokens are the new style identifiers... 8-(I'm trying not to think about that Fortunately I don't think it's _quite_ that bad. -- http://mail.python.org/mailman/listinfo/python-list
rot13 in a more Pythonic style?
I'm trying to write rot13, but to do it in a better and more Pythonic
style than I'm currrently using. What would you reckon to the
following pretty ugly thing? How would you improve it? In
particular, I don't like the way a three-way selection is done by
nesting two binary selections. Also I dislike stating the same
algorithm twice, but can't see how to parameterise them neatly.
Yes, I know of .encode() and .translate().
No, I don't actually need rot13 itself, it's just a convenient
substitute example for the real job-specific task.
No, I don't have to do it with lambdas, but it would be nice if the
final function was a lambda.
#!/bin/python
import string
lc_rot13 = lambda c : (chr((ord(c) - ord('a') + 13) % 26 + ord('a')))
uc_rot13 = lambda c : (chr((ord(c) - ord('A') + 13) % 26 + ord('A')))
c_rot13 = lambda c : (((c, uc_rot13(c)) [c in
'ABCDEFGHIJKLMNOPQRSTUVWXYZ']), lc_rot13(c) )[c in
'abcdefghijklmnopqrstuvwxyz']
rot13 = lambda s : string.join([ c_rot13(c) for c in s ],'')
print rot13( 'Sybevk Tenohaqnr, Fcyhaqvt ihe guevtt' )
--
http://mail.python.org/mailman/listinfo/python-list
Re: rot13 in a more Pythonic style?
On 14 Feb, 16:23, Neil Cerutti [EMAIL PROTECTED] wrote: str.translate is what I'd do. That's what I hope to do too, but it might not be possible (for the live, complex example). It looks as if I have to make a test, then process the contents of the code differently depending. There might well be a translation inside this, but I think I still have to have an explicit 3-way switch in there. How would it being a lambda help you? I'm going to use it in a context where that would make for cleaner code. There's not much in it though. I still don't understand what a lambda is _for_ in Python. I know what they are, I know what the alternatives are, but I still haven't found an instance where it permits something novel to be done that couldn't be done otherwise (if maybe not so neatly). -- http://mail.python.org/mailman/listinfo/python-list
Re: How can I access data from MS Access?
On 5 Feb, 19:40, Sells, Fred [EMAIL PROTECTED] wrote: Years ago we used to get our FORTRAN card decks back from the DP center with a piece of scrap paper saysing She No Work. top that. I used to use a cross-compiler (targetting some obscure single-chip hardware) that had just a single error message Diddley-squat somewhere near here -- http://mail.python.org/mailman/listinfo/python-list
Re: How can I access data from MS Access?
On 3 Feb, 15:43, [EMAIL PROTECTED] wrote: How to access data from MS Access? Can you access Access from Access ? from Excel / Visual Basic / SQL Query? First of all check that the DSN is working and connects to the back end MDB. This might not be Python's problem. Secondly check whatever errors you're being returned. -- http://mail.python.org/mailman/listinfo/python-list
Python tools to manipulate JARs ?
I run build processes for a Java shop using Python (and some Ant). Would anyone care to suggest favoured tools for manipulating the innards of JARs? Or do I just treat them as plain zipfiles and get stuck right in there? Mainly I'm trying to query lists of classes and their embedded versions and do some library dependency reporting. Performance speed is starting to be an issue, as there's 1500+ classes in this bucket and it's an interactive query. Thanks for any suggestions -- http://mail.python.org/mailman/listinfo/python-list
Re: program deployment
king kikapu wrote: Are they embarassed by their code? hehehe...no, just worried about stealing their ideas... Ever heard of Open Source ? I do better by letting other people steal my ideas (and stealing theirs too) than I'd ever do by keeping things secret. -- http://mail.python.org/mailman/listinfo/python-list
Re: One module per class, bad idea?
Matias Jansson wrote: I come from a background of Java and C# where it is common practise to have one class per file in the file/project structure. Don't confuse packages and files. Java commonly splits a package across many files, Python binds a module to a single file. If you see Java package as more comparable to Python module then the difference in how many classes are in a file becomes unimportant. Java also puts many classes in the same source file, if they're tightly coupled (e.g. Swing UI). It spits them out into separate .class files though. -- http://mail.python.org/mailman/listinfo/python-list
Re: dict.has_key(x) versus 'x in dict'
Paul Melis wrote: I've always been using the has_key() method to test if a dictionary contains a certain key. Recently I tried the same using 'in', e.g. I've found using the set type to be the quickest way to do many of these tasks. That leads me to another problem: how to cast / convert sets as something else afterwards What's the best (i.e. Pythonic) way to do this? I need to generate a set (lots of intersections involved), but then I need to display it sorted lstBugsChanged = [ bugId for bugId in setBugsChanged ] lstBugsChanged.sort() -- http://mail.python.org/mailman/listinfo/python-list
Re: dict.has_key(x) versus 'x in dict'
Roberto Bonvallet wrote: lstBugsChanged = [ bugId for bugId in setBugsChanged ] In Python 2.4: Hmmm. Thanks. Another reason to twist the admin's arm and get them to upgrade the last 2.3.4 boxen sorted(setBugsChanged) Out of interest, whats the Pythonic way to simply cast (sic) the set to a list, assuming I don't need it sorted? The list comprehension? -- http://mail.python.org/mailman/listinfo/python-list
Re: rdf, xmp
Imbaud Pierre wrote: I have to add access to some XMP data to an existing python application. XMP is built on RDF, I'm just looking at the XMP Spec from the Adobe SDK. First impressions only, as I don't have time to read the whole thing in detail. This spec doesn't inspire me with confidence as to its accuracy and consistency. I think I've already seen some obscure conditions where developers will be unable to unambiguously interpret the spec. Compared to MPEG-7 however, at least it's not 700 pages long! The spec does state that property values can be structured, which is one of the best reasons to start using RDF for storing metadata. However I think actual use of these would be minimal in typical XML applicaations. At worst it's a simple data typing exercise of a two-valued tuple for dimensions, rather than separate height and width properties. These are no problem to process. In particular, the XMP data model is a single-rooted tree, i.e. there is an external model of a resource (i.e. one image file) and an XMP document only addresses a single resource at a time. A major restriction in XMP is that it has no concept of shared resources between properties (and it can't, as there's no rdf:ID or rdf:about allowed). This is always hard to process, but it's also very valuable for doing metadata. Imagine a series of wildlife images that all refer to a particular safari, national park and species. We might be able to share a species reference between images easily enough by referring to a well-known public vocabulary, but it would also be useful (and concise) to be able to define one expedition in a subject property on one image, then share that same resource to others. As it is, we'd have to duplicate the full definition. Even in XMP's separate document for each image resource model we still might wish to do something similar, such as both photographer and director being the same person. When you start having 20MB+ of metadata per video resource (been there, done that!) then this sort of duplication is a huge problem. Not just because of the data volume, but because we need to identify that referenced resources are identical, not merely havingg the same in their property values (i.e. I'm the same John Smith, not just two people with the same name). There is no visible documentation of vocabularies, inetrnal or external. Some pre-defined schemas are given that define property sets, but there's nothing on the values of these, or how to describe that values are being taken from a particular external vocabulary (you can do this with RDF, but they don't describe it). This isn't widely seen as important, except by people who've already been through large media annotation projects. It's RDF-like, not just XML. However it's also a subset of RDF - in particular rdf:about isn't supported, which removes many of the graph structure constructs that make RDF such a pain to process with the basic XML tools. Read their explicit not on which RDF features aren't supported -- they're enough to make XMP easily processable with XSLT. The notes on embedding of XMP in XML and XML in XMP are both simplistic and ugly. I still don't see much _point_ in XMP. I could achieve all this much with two cups of coffee, RDF and Dublin Core and a whiteboard pen. Publishing metadata is good, publishing new _ways_ of publishing metadata is very bad! Overall, it could be far better, it could be better without being more complicated, and it's at least 5 years behind industry best practice for fields like museums and libraries. It's also a field that's still so alien to media and creative industries that the poor description and support of XMP will cause them to invent many bad architectures and data models for a few years to come. -- http://mail.python.org/mailman/listinfo/python-list
Re: rdf, xmp
Imbaud Pierre wrote: I have to add access to some XMP data to an existing python application. XMP is built on RDF, RDF is built on XML. RDF is _NOT_ built on top of XML. Thinking that it is causes a lot of trouble in the architecture of big RDF projects. RDF is a data model, not a serialisation. The data model is also a graph (more than XML can cope with) and can span multiple documents. It's only RDF/XML that's the serialisation of RDF into XML and good architectures start from thinking about the RDF data model, not this RDF/XML serialisation. As to RDF handling, then the usual toolset is Jena (in Java) and Redland has a Python binding although Redland is fairly aged now. I'm unfamiliar with XMP and won't have a chance to look at it until Monday. However if XMP is strongly XML like despite claiming to be RDF, then you might find that handling a pure XMP problem is quite easily done with XML tools. Famously RDF/XML is unprocessable with XSLT if it's sophisticated, but quite easy if it's restricted to only a simple XML-like RDF model. XMP could well be similar. -- http://mail.python.org/mailman/listinfo/python-list
Re: Printing Barcodes from webapp?
Burhan wrote: Is there an easy way to generate barcodes using Python Easy way for any application or language to generate barcodes is to install a barcode font on the client machine, then just generate a suitable text string for it. This is _very_ easy, if you can get the font deployed. I usually find myself using Code 39 and printing them from a HTML document. There are plenty of free code 39 fonts around and the string mangling to get the barcode structured correctly is just a trivial prefix / suffix. -- http://mail.python.org/mailman/listinfo/python-list
Re: Python v PHP: fair comparison?
walterbyrd wrote: I don't know if this is a fair comparison or not. Who cares? Anything involving PHP is a billion flies can't be wrong type of statement. I agree completely with your observation about PHP's lower cost of access. This is ostensibly a good thing, but it also means that every software-ignorant newbie dives straight into PHP and ten minutes later they're a guru. The average quality of PHP developers is rock-bottom and the average quality of PHP code is about the same. I don't like the language either, but it's the use PHP is put to that spoils most of it, more than language features itself. -- http://mail.python.org/mailman/listinfo/python-list
Re: HTML Parsing and Indexing
[EMAIL PROTECTED] wrote: I am involved in one project which tends to collect news information published on selected, known web sites inthe format of HTML, RSS, etc I just can't imagine why anyone would still want to do this. With RSS, it's an easy (if not trivial) problem. With HTML it's hard, it's unstable, and the legality of recycling others' content like this is far from clear. Are you _sure_ there's still a need to do this thoroughly awkward task? How many sites are there that are worth scraping, permit scraping, and don't yet offer RSS ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Book about database application development?
Paul Rubin wrote: http://philip.greenspun.com/sql/ There was a time (some time in the mid 90s) when I thought that Philip Greenspun had a Clue. Then I realised just how wrong he was (he started off reasonably right, he just didn't keep up when the world moved on). The highlight of this process was seeing him booed during a conference keynote speech -- by angry librarians and museum curators (he deserved it too). I can't imagine any topic, except possibly dog grooming, where I'd listen to his advice. -- http://mail.python.org/mailman/listinfo/python-list
Re: Where is Python in the scheme of things?
gord wrote: As a complete novice in the study of Python, I am asking myself where this language is superior or better suited than others. I use it, and see it primarily, as a Perl killer. It also does for Ruby and our infernal shell scripts. I've never considered using Python instead of VB. As a VB developer of many years, I'd see thhe Python language itself as infinitely superior to VB in almost every aspect, except that of building event driven Windows GUIs with easy form layout. Maybe there's some wonderful Python toolkit for doing this, but it's news to me. I'm undecided as to whether Python beats JSP for web development. So far I'm still inclined to Java, but that's probably because I know Java and Java has a huge amount of beyond Java the language development attached to it for web work. -- http://mail.python.org/mailman/listinfo/python-list
Re: does anybody earn a living programming in python?
walterbyrd wrote: If so, I doubt there are many. I currently earn my living programming in Python. This is particularly amusing given that it's a Java shop and I don't even know Python! I've only been using it for a few months as a replacement for the previous shell scripts and instead of Perl (which I know, but never liked). I'm nominally the release manager which is half tiresome monkey work and half is building vast Python-powered scripts to automate the aforementioned monkey work. I don't think I've written more than a line of actual Java since I've been there. One thing is sure though - I wouldn't have been _recruited_ as a Python coder. Supposedly they hired me on the strength of all-round experience and as a Java hack. -- http://mail.python.org/mailman/listinfo/python-list
Re: Looking for a regexp generator based on a set of known string representative of a string set
[EMAIL PROTECTED] wrote: I am looking for python code that takes as input a list of strings [...] and outputs the python regular expression (s1|s2|s3|s4|s5) for strings of s1 etc. Regex compilers are themselves quite good at optimising beyond this -- http://mail.python.org/mailman/listinfo/python-list
Re: python vs java
Aravind wrote: some of my friends told that python and java are similar in the idea of platform independency. Similar in goal, but quite different in approach. Python supports lots of platforms and goes to great lengths to offer facades around whatever features a platform does have, so as to offer the same benefits as Unix. Java lives in a virtualised environment where it pretends there aren't any platforms. Perl pretends everything _is_ Unix and falls flat when it isn't. If you can cope with this, Java is simpler and less platform-bound. If you actually need to get OS-level work done, Python is wonderful. You can write stuff that hooks in at a fairly deep level, yet really is portable. -- http://mail.python.org/mailman/listinfo/python-list
Newbie - How to iterate list or scalar ?
I seem to be writing the following fragment an awful lot, and I'm sure it's not the best and Pythonic way to do things. Any advice on better coding style? pluginVersionNeeded is a parameter passed into a method and it can either be a simple scalar variable, or it can be a list of the same variables. My problem is how to iterate it, whether it's a a list or not. I can't simply throw it into the for...in loop -- if the scalar variable were to be a string (which is considered to be atomic in my application) then Python sees this string as iterable and iterates over the characters in it! versionsNeeded = pluginVersionNeeded if isinstance( versionsNeeded, list): versionsToTest = versionsNeeded else: versionsToTest = [ versionsNeeded ] for versionNeeded in versionsToTest: pass Thanks for any advice -- http://mail.python.org/mailman/listinfo/python-list
Re: do people really complain about significant whitespace?
Thomas Guettler wrote: I like python, but sometimes i don't like that python allows spaces and tabs. It would be easier if you had less choice and must use four spaces. That's the nice thing about Python. It doesn't care about indentation distance, it just wants some and consistent. I like the idea that humans see the whitespace as significant anyway, so document the fact and use it (I presume this came from Occam). What I don't like so much is that the _ends_ of blocks are less visually obvious. -- http://mail.python.org/mailman/listinfo/python-list
Re: Newbie - How to iterate list or scalar ?
Bruno Desthuilliers wrote: there's really no reason to assume it should be a list - any iterable could - and IMHO should - be accepted... expect of course for strings (royal PITA case, duh). 2/ test for pluginVersionsNeeded.__iter__ (an attribute of most iterables except strings...): strings don't have __iter__ ?!?! I'm never going to get my head round this language 8-( I can understand strings and tuples being iterable, if you take a sufficiently first-class view of things, but why shouldn't everything that is iterable support the function that makes iteration work? -- http://mail.python.org/mailman/listinfo/python-list
Re: Windows vs. Linux
[EMAIL PROTECTED] wrote: Python and Ubuntu rock...go fot it. That's nice. I've just burned myself a new Ubuntu f*ck-a-duck release CD intending to rebuild a flakey old Deadrat box with it. Once it's done I'd like to be running Python with some USB to Dallas one-wire hardware on it, re-plugged from an old Windows box. Nice to know I have a hope of getting somewhere. -- http://mail.python.org/mailman/listinfo/python-list
Re: Windows vs. Linux
[EMAIL PROTECTED] wrote: Is Windows an okay enviornment in which to program under Python, or do you recommend that I run a dual-boot of Linux or maybe a VMWare install to program under Python? Python is one of the best languages I've found for platform-independence - significantly better than Perl. Right now I'm coding Python that runs happily under Redhat, Windows /Cygwin and Windows native. It also integrates closely with command line tools like subversion, including piping their output into Python-based XML parsers. This really wouldn't be easy with Perl. Find yourself an editor that's pretty similar under both Unix and Windows. jEdit is a good place to start. You might also like to look at running Cygwin under Windows. It's a Unix-like command shell that provides nearly every command-line Unix tool you could want on a Windows box. Can be a little awkward at times, but it's a huge advantage over raw Windows. I'd never recommend dual-boot for anything! Hardware is cheap, time and trouble is expensive. -- http://mail.python.org/mailman/listinfo/python-list
Re: range() is not the best way to check range?
[EMAIL PROTECTED] wrote: it seems that range() can be really slow: if i in range (0, 1): RTFM on range() You're completely mis-using it here, using it with an if ... in ... test. The purpose of range() in Python is as loop control, not comparisons! It's not a SQL BETWEEN statement. Although you _can_ do this (you've done it!) you've also found that it's slow. Many people would argue that even using range() for loop control is unusably slow. -- http://mail.python.org/mailman/listinfo/python-list
Re: list comprehension
Simon Forman wrote: There's more to it, but that's the basic idea. This much I knew, but _why_ and _when_ would I choose to use list comprehension (for good Python style), rather than using a simple traditional loop ? If I want to generate something that's simply ( [1] + [2] + [3]+... ) then list comprehension is obviously the tool of choice. I suspect though that there's more to it than this. Is list comprehension also treatable as a sneaky concise formulation for nested lists, where they're as much about selection of individual elements, so much as concatenation of the sequence? What happens if a comprehension has side effects, such as from calling a function within it? Is this regarded as good or bad coding style? Is it evil (as structured programming would claim) or is it a concise formulation for an iterator or visitor pattern ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in HTML
[EMAIL PROTECTED] wrote: Python, like it's (evil?) cousin Perl, Isn't that evil cousin Ruby? Perl's the mad old grandmother in the attic, spewing out incomprehensible [EMAIL PROTECTED]% swearing all day. can be used as a CGI. If you don't have one already, go download Apache server to play with on your own machine and Google Python CGI and Python module cgi. Or if you're cursed with IIS for Windows, then PythonScript does the job. -- http://mail.python.org/mailman/listinfo/python-list
[newbie] Iterating a list in reverse ?
Python newbie: I've got this simple task working (in about ten different ways), but I'm looking for the favoured and most Python like way. Forwards I can do this for t in listOfThings: print t Now how do I do it in reverse? In particular, how might I do it if I only wanted to iterate part-way through (with a conditional test and a break), or if I had a large list ? reverse( listOfThings ) for t in listOfThings: print t As reverse() operates in-place I often can't do this. I'm also (slightly) concerned about possible inefficiency issues of manipulating a big list just to scan a peek at its tail. Currently I'm doing this: for i in range( len( listOfThings )-1, 0, -1): t = listOfThings [i] print t Is this the optimum ? Would xrange() be a better choice (and when is it a big list) ? Thanks for any guidance -- http://mail.python.org/mailman/listinfo/python-list
Re: Iterating a list in reverse ?
Fredrik Lundh wrote: for item in reversed(listOfThings): Thanks! I was staring so hard at reverse() that I'd completely missed reversed() I think I prefer this to listOfThings[::-1]: as it's a little more readable. Not that I'm reacting to past bad experience of Perl, you understand 8-) -- http://mail.python.org/mailman/listinfo/python-list
Re: Xah's Edu Corner: The Concepts and Confusions of Pre-fix, In-fix, Post-fix and Fully Functional Notations
On Fri, 17 Mar 2006 11:22:06 +0100, Timo Stamm [EMAIL PROTECTED] wrote: Xah's posting was properly encoded and will display fine in every decent newsreader. Well mine killfiled it straight off, which I think is entirely proper rendering for one of Xah Lee's kookery lessons. -- http://mail.python.org/mailman/listinfo/python-list
