Re: pythonOCC examples doesn't work?
You installed python 2.7 and expect a 2.6 module to work with it. That won't work. Finally, you need to install the OpenCasCade libs to be able to run PythonOCC. -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Modules and Namespaces
Dear Steve & Larry, Both your methods worked flawless, thanks to both of you! I have to say Larry's way wins on style points, doens't it? What an awefull thing to get stuck on something that simple, what a gorgeous solution, thanks so much! -Jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Modules and Namespaces
Ooops, Larry, forgive me being to overhauled here: Actually self.RS = RS does not make the RS object available in the module, Steve's method does however. -Jelle -- http://mail.python.org/mailman/listinfo/python-list
Should i pick up Numeric, Numarray or SciPy.core?
#No rant intended I'm not at all confused wether I should learn an one of the advanced array modules, I'm slightly confused over which I should pick up. I'm impressed with the efforts of SciPy and Scientific, but since I'm fairly new to programming & OO, choosing Numarray over Numeric hasnt been that satisfactory at all, which is not a problem of the quality of Numarray, but the fact that a lot of modules still heavily realy on Numeric. Which, with my fragile knowledge in programming is rather confusing sometimes. Since its seems its far from pragmatic to opt solely for either one of them. So Scipy.core looks like the ticket for me here, doesnt it? Before putting an effort into it, I'd like to know whether this would make sense, certainly since scipy.core is in its early stages, and documentation isnt available yet (for free that is... its not clear to me why I should pay for software in its early stages, when it extents on efforts freely available) Curious for your opinions, I definitely think the Scipy.core effort is terrific, but right now I'm wondering whether its a pragmatic choice. -Jelle -- http://mail.python.org/mailman/listinfo/python-list
SciPy python 2.4 wintel binaries
Hi, I dearly miss having the power of SciPy on my python 2.4 installation. The topic of SciPy python 2.4 wintel binaries has been discussed before on this list, but I haven't been able to find a compiled binary. I'm one of the 'compiled-challenged'; anything more complex than 'python setup.py build' leaves me at the grace of the non-challenged... SciPy is a complex software engineering project, so I'm hangin on the mercy of others here... Is anyone on this list aware of such a binary? Thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: SciPy python 2.4 wintel binaries
Hi Peter, I'm aware of the Enthought distribution, which really is my preferred 2.3 Python distribution. Problem is that many programs I'm working on would require both 2.4 & SciPy What kind of puzzles me is that SciPy.core is available for wintel 2.4, is that an indication a full SciPy distribution is coming along? Cheers, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: SciPy python 2.4 wintel binaries
Claudio, Thanks a lot for this link! -- http://mail.python.org/mailman/listinfo/python-list
Re: ElementTree - Why not part of the core?
Doug, I agree with you, ElementTree is fast & pythonic. Certainly does make sense to me. -- http://mail.python.org/mailman/listinfo/python-list
quering the google desktop database
Hi, Has anyone so far been messing accessing / quering the google desktop database files? It seems it could be the best reflection of one in a couple of hundred mb, and i intent to unleash some furious queries on it, when i'd know how to access it. Any suggestion how this could be done in python? My intention is to apply data mining to the google desktop database. How about it, who's in for it? Cheers, Jelle -- http://mail.python.org/mailman/listinfo/python-list
future of computing languages
Quite suprised while reading the Amazin c2.com Wiki: http://c2.com/cgi/wiki?FutureOfProgrammingLanguages Take a look, and feel incredible good about yourself & your decision to opt for python. Did work for me. Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
pythonic equivalent of Mathematica's FixedPoint function
I now some hostility to functional programming is flaming up now and then; still could someone suggest me a pythonic equivalent for Mathematica's FixedPoint function? For those not familiar with Mathematica: FixedPoint[f, expr] starts with expr, then applies f repeatedly until the result no longer changes. thanks, jelle. -- http://mail.python.org/mailman/listinfo/python-list
Re: pythonic equivalent of Mathematica's FixedPoint function
doh... https://sourceforge.net/projects/fixedpoint pardon me -- http://mail.python.org/mailman/listinfo/python-list
Re: pythonic equivalent of Mathematica's FixedPoint function
Ah, i see, that clears up the monetary context. Thank you for your FixedPoint example. Can i help myself out by mentioning that the most simple things are always most difficult ;-) Thanks, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
Re: pythonic equivalent of Mathematica's FixedPoint function
>You could probably write your own FixedPoint function without too much >difficulty, with the only tricky part being for it to know when to stop! It would be quite interesting to have this kind of function. But likely its far from trivial. FixedPoint seems to be one of the core functions in Mathematica, where many other functions are based on. Some additions such as FixedPoint would make functional programming in Python more functional is suppose. Or would anyone consider it sugar syntax for ?? -- http://mail.python.org/mailman/listinfo/python-list
connecting to an exsisting COM server
Hi, I'm using win32com.client.GetObject(Class='Rhino3.Application') to connect to an existing COM server. However when doing so: Traceback (most recent call last): File "", line 1, in ? File "C:\Python24\lib\site-packages\win32com\client\__init__.py", line 80, in GetActiveObject dispatch = pythoncom.GetActiveObject(resultCLSID) com_error: (-2147221021, 'Operation unavailable', None, None) A com_error is raised. This problem has come up a few times on this list, however that didn't help me to find a way of connecting to it. What else could I try? Cheers, Jelle -- http://mail.python.org/mailman/listinfo/python-list
Cancelling a subprocess based on its output
Hi, I'm using the subprocess module to run a open-source lighting simulation software, Radiance, and am using python to script it. When Radiance finds a scene where no light is present its prints out 'warning - no light sources found' to the console. I'm looking for a way to terminate the subprocess when this message is spitted out to the console. Searching this forum on subprocess & stderr didn't lead to a clue to solving this problem. I'm using both win32 & linux to run these simulations, so a cross-platform way of doing this is important. Any suggestions? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
how to pass an array to a VB array via COM
Hi, I'm trying to script Rhino -the nurbs modeller, not the server soft- via COM. Which is good fun, except i cant seem to pass arrays to the program. I suppose its expecting VB arrays, and is not to keen when i send a tuple: RS.AddCurve(((1,2,3),(4,5,6),(7,8,9)),3) --- Traceback (most recent call last): File " ", line 1, in ? File "c:\Python23\lib\site-packages\jf\interface\RhinoScript.py", line 48, in AddCurve return self._ApplyTypes_(77, 1, (12, 0), ((12, 0), (12, 16)), 'AddCurve', None,vaPoints, vaDegree) File "c:\Python23\lib\site-packages\win32com\client\__init__.py", line 446, in _ApplyTypes_ return self._get_good_object_( com_error: (-2147352567, 'Exception occurred.', (6, 'RhinoScript_m', 'Type mismatch in parameter. One-dimensional array required.', 'C:\\Program Files\\Rhinoceros 3.0\\RhinoScript_m.HLP', 393222, 0), None) --- This is somewhat puzzling, since when i define points in the application, these are returned as a tuple of tuples: >>>s = RS.GetPoints() >>>print s ((-7.0, -30.0, 0.0), (15.0, -24.0, 0.0), (-7.0, 12.0, 0.0), (14.0, 29.0, 0.0), (28.0, 10.0, 0.0), (20.0, 1.0, 0.0)) I've been searching this list for a solution, but didnt find anything i could use. Any ideas? Cheers, Jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: how to pass an array to a VB array via COM
No I haven't, it might be an idea. Would it be an effective method though? I have little experience working with COM, but i suppose writing an (VB!) array wouldnt be the most challenging problem, though browsing through this list it looks like no good solution arrived yet. Cheers, Jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: how to pass an array to a VB array via COM
Thomas, No, i went over the syntax extensively. The syntax is RS.AddCurve(points, degree), so 3 represents the degree of a bezier curve. I'm doing fine with all types of functions which use 2 x,y,z coords, but all arrays -tuple of tuples- fail. The odd thing is that when i use RS.GetPoints() which is a method to get back user-defines x,y,z points, i get a tuple of tuples containing these points. Though when i write these back to the program, all fails: I admit posting this problem also to the more specific python-win32 group, though no response there yet... >>>s = RS.GetPoints() >>>s ((-7.0, -30.0, 0.0), (15.0, -24.0, 0.0), (-7.0, 12.0, 0.0), (14.0, 29.0, 0.0), (28.0, 10.0, 0.0), (20.0, 1.0, 0.0)) Cool, I get to choose points in the GUI, right back into python, wicked! Though when I send these points back to the app: RS.AddPolyline(s) The same error all over again: --- Traceback (most recent call last): File " ", line 1, in ? File "c:\Python23\lib\site-packages\jf\interface\RhinoScript.py", line 129, in AddPolyline return self._ApplyTypes_(85, 1, (12, 0), ((12, 0),), 'AddPolyline', None,vaPoints) File "c:\Python23\lib\site-packages\win32com\client\__init__.py", line 446, in _ApplyTypes_ return self._get_good_object_( com_error: (-2147352567, 'Exception occurred.', (6, 'RhinoScript_m', 'Type mismatch in parameter. One-dimensional array required.', 'C:\\Program Files\\Rhinoceros 3.0\\RhinoScript_m.HLP', 393222, 0), None) --- -- http://mail.python.org/mailman/listinfo/python-list
Re: how to pass an array to a VB array via COM
Hi Stefan, Thanks for your insightful and in-depth response! Wonderful to hear that a solution is in the works, that's absolutely wonderful news. If I can help you out beta-testing the PySafeArray implementation, I'd be delighted to do so. Thanks again, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
PyQT dll's | missing qt-mtedu333.dll
Hi, I'm trying to run a python program which requires PyQt, which is installed properly on my machine, but unfortuanately it doesn't come with the required .dll to run the .pyd's, I'm missing qt-mtedu333.dll. This version is no longer available from trolltech, and I hope perhaps someone could spare me the effort of finding and compiling v3.3.3? thank, jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Graphviz/dot language formatter
Hi, the recently added boost.graph python binding could be most useful: http://www.osl.iu.edu/~dgregor/bgl-python/#download -- http://mail.python.org/mailman/listinfo/python-list
csrss.exe & Numeric
I have a function that uses the Numeric module. When I launch the function csrss.exe consumes 60 / 70 % cpu power rather than having python / Numeric run at full speed. Has anyone encountered this problem before? It seriously messes up my Numeric performance. I'm running 2.4.2 on xp. Cheers, Jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Vector math library
martin, pyformex has a vector module as well. its not very pythonic, but it could help you out creating a version of your own. worth checking out -- http://mail.python.org/mailman/listinfo/python-list
Re: Best IDE for Python
I think SPE is a terrible complete and efficient IDE! -- http://mail.python.org/mailman/listinfo/python-list
Re: help a newbie with a IDE/book combination
I think SPE is a terrific IDE, a real pleasure to work with! Also it's very complete in terms of functionality. http://stani.be/python/spe/page_download -- http://mail.python.org/mailman/listinfo/python-list
CGAL bindings
Hi, I'm wondering whether anyone is aware of efforts being made wrapping the CGAL library? It's a highly advanced computational geometry library, see cgal.org -j //any other computational geometry links appreciated... -- http://mail.python.org/mailman/listinfo/python-list
adding a docstring to an instancemethod
Hi, I'm working on documenting wrapped C++ methods. The thing is that I'd like to add docstrings to a method, but python won't allow me to: TypeError: attribute '__doc__' of 'instancemethod' objects is not writable What would be an easy way to do so? I'd like to overload the .__doc__, rather than wrapping it in a class. Cheers, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: adding a docstring to an instancemethod
Hi Gabriella, thanks for pointing me in the right direction: eo.eoTruncatedSelectOne.setup.im_func.func_doc = 'method string goes here' works beautifully! cheers, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: adding a docstring to an instancemethod
> Set the __doc__ on the *function* from which you build the instance method. Thanks for you reply Gabriel, Though setting the docstring to the functions wouldn't be an option for me. The thing is that I have a wrappedCppModule.Class.Method I'd like to give a docstring, so there's no prior function to refer to. Thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
initializing cooperative method
Hi, I'm writing a bunch of abstract classes and I'd like to delegate the arguments of the concrete class the to abstract one. I was surprised to see that the print statement in the abstract class isn't executed. But moreover, I'd like to find out an idiom that allows one to delegate arguments in the inherited class. Any ideas? Thanks, -jelle class Abstract(object): def __init__(self, a='a', b='b'): self.a, self.b = a, b print a, b class Concrete(Abstract): def __init__(self, a='AAA', b='BBB'): super(Abstract, self).__init__( a=a, b=b ) print a, b c = Concrete(a=1) >>> c = Concrete(a=1) 1 BBB -- http://mail.python.org/mailman/listinfo/python-list
Re: initializing cooperative method
Ai, calling super(Abstract) is just getting object, sure... However, I'm still curious to know if there's a good idiom for repeating the argument in __init__ for the super(Concrete, self).__init__ ? Thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: initializing cooperative method
Ai, calling super(Abstract) is just getting object, sure... However, I'm still curious to know if there's a good idiom for repeating the argument in __init__ for the super(Concrete, self).__init__ ? Thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
shouldn't 'string'.find('ugh') return 0, not -1 ?
the subject pretty much says it all.
if I check a string for for a substring, and this substring isn't found,
should't the .find method return 0 rather than -1?
this breaks the
if check.find('something'):
do(somethingElse)
idiom, which is a bit of a pity I think.
cheers,
-jelle
--
http://mail.python.org/mailman/listinfo/python-list
Re: shouldn't 'string'.find('ugh') return 0, not -1 ?
>if 'something' in check: > do(somethingElse) Tim, you're absolutely right that the above makes far more sense in my case. Thanks for pointing that out. -jelle -- http://mail.python.org/mailman/listinfo/python-list
Shell like syntax for subprocess.Popen # overloading >, <, |
Hi,
I use python quite a bit to couple different programs together.
Doing so has been a _lot_ easier since subprocess came around, but
would really like to be able to use the succinct shell syntax; >, <, |
That really shouldn't be too hard to wrap in a class, but so far I
didn't succeed to do so this well, since I'm facing some trouble with
operator precedence that I do not know how to overcome.
Consider the following:
A = 'inputString'
B = Process('process.exe')
C = cStringIO.StringIO() # output bucket
A > B > C
A is being piped to B and processed, but the output of B is not being
piped to C
executing A > B; B > C works as expected however.
Which is disappointing, since what I'm trying to achieve is a sugar
syntax for Popen processes, where directly sees the chain of
commands...
Any suggestions to overcome this issue are greatly appreciated!
cheers,
-jelle
-
class Process(Popen, object):
def __init__(self, commandString, wait=False):
assert isinstance(commandString, str)
cmd = commandString.split()
self.cmd= commandString
self.exe= cmd.pop(0)
##self.args = cmd
self.process = Popen(self.cmd, shell=True, stdin=PIPE,
stdout=PIPE, close_fds=False)
self.stdout = self.process.stdout
self.stderr = self.process.stderr
def __repr__(self):
return 'Process instance ( %s ) ' % (self.exe)
def __or__(self, other): # PIPE
'''
returns the output of Process A -> Process B
takes a Process instance as argument
'''
assert isinstance(other, Process), '%s\n is not a Process
instance' % (other)
print 'PIPE'
self > other
def __lt__(self, other): # STDIN
'''
takes a StringIO, file or string objectas argument
'''
print '>'
print 'STDIN'
if isinstance(other, str):
self.process.communicate(other)
else:
self.stdout, self.stderr =
self.process.communicate(other.read())
self.process.wait()
def __gt__(self, other): # STDOUT
'''
takes a StringIO, file or string object as argument
returns the result of an external process
'''
print '<'
print 'STDOUT'
assert hasattr(other, 'write') or isinstance(other, str)
if isinstance(other, str):
other += self.stdout
else:
other.write(self.stdout)
-
--
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Re: Shell like syntax for subprocess.Popen # overloading >, <, |
Hi Christos, Thanks for your pointers there, impressive to see -that a 12 year old thread still can make an interesting read -you being able to remember & trace it... impressive... Thanks for your pointers. I think the input > process > output Syntax is more powerful , since it would let you build chaining commmands in a more readable fashion. The goal of this class would be to construct command chains such as: input > processA | processB > ouput Something which wouldn't be possible if only one operator is overloaded. I'm curious to see if its doable via overloading, since no __rgt__ methods exists... -- http://mail.python.org/mailman/listinfo/python-list
are docstrings for variables a bad idea?
That's basically the idea...
Often i find myself annotating what variables actually stand for, so to
refer back to the code in half a year or so.
# check if ID's or coords
self.pointIDs = ptIDs
self.coords = [tuple(RS.PointCoordinates(i)) for i in ptIDs]
# map ids/coords and coords/ids
self.pointID_2_Coord, self.coord_2_pointID = {}, {}
for id, coord in zip(self.pointIDs,self.coords):
self.coord_2_pointID[coord] = id
self.pointID_2_Coord[id]= coord
# initiate kdtree
self.kdTREE = kdtree.kdtree(3)
for i in self.coords:
self.kdTREE.addPoint(i)
# break down interfaceCrvID
self.segments = list(RS.ExplodeCurves(interfaceCrvID))
# dictionary with a midpoint for each segment
self.segmentCoords = {}
for i in self.segments:
self.segmentCoords[i] = list(RS.CurveMidPoint(i))
and so on...
Please don't say that naming variables properly suffices for any
skilled programmer... really...
When programming a more complex class, it would be quite helpful that
these annotations would pop-up as a docstring.
Often I find myself referring back to a module containing the class to
read back what data the variable holds exactly. A time consuming
activity that could be seriously sped up by a proper IDE
(I'm on SPE, thanks Stani!)
Would that make sense to anyone?
cheers,
-jelle
--
http://mail.python.org/mailman/listinfo/python-list
Re: are docstrings for variables a bad idea?
---I don't know for sure what you mean by "pop up as doc-string" - I guess you want them magically merged into the functions doc string, at least inside your editor? That sure could be done - but I personally don't think that is too useful. Because you lose context.--- point taken. perhaps only variables declared in the __init__ should be made available as a doc string. ---IMHO commenting the parameters and results of a function is what someone needs who skims the docs for enlightenment--- these are two completely different things: f = instanceSomeClass() -> 'pops up the __init__ doc string in your IDE' now, when this class is instanced, i think this could be useful: f.someComplexMethod -> 'pops up the variable docstring' I'm all for DRY -dont repeat yourself-, but DHORYEBNPTMTRYCEBPTSWTITDS -don't have others repeat your efforts by not providing the means to reuse your code efficiently by providing them sparsely with the information to do so- could have some place in complex classes that are often subclassed. having the right information at the right time to do so would be quite a help. be fair: do you perfectly well know how to subclass a class without (extensively) reading it back? perhaps a variable doc here and there would make this slightly easier. -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: are docstrings for variables a bad idea?
didn't you just do that ;') such variables docstrings would help one to speed up understanding an API, and more importantly, could reduce assumptions you make on what a variable means. who's the mother of assumptions again? i'm not evangalizing at all that each and every variable should be documented! but one cannot deny there is a certain degree of entropy in the understanding of classes you even wrote yourself. so variables docstrings could be very helpful notes to oneself and others. imagine you wrote a python script that runs a FEM simlation overnight, relating drag to speed. rcar.speed -> 'resulting velocity to rcar.drag' these little notes could help you not to make the same false assumption you've overcome a year ago, and are likely to make again. also in cases (most) where you are not the sole operator on a class, these little hints can be appreciated. a variables doctring should never be longer than 2 lines to be any good likely. ok. 3 -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: are docstrings for variables a bad idea?
Hi Diez, please take note, this suggestion does not nessecarily apply to programmers such as you & myself of course for whom any python code is as transparant as the API's we write ;') I feared that you meant that - but wasn't sure. This is one of the often-requested-yet-they-will-never-come features of IDEs for python, as this would mean that you'd have type-information available on f. Consider this simple example: f = someRandomlyInstatiatedObject() Now what is e.g. f. to show? why is this ambigious at all? am i seriously overlooking something? class jelle: def __init__(self): ''' we've been having this for a while, just the helpful constructor docstring ''' '''relates drag to speed''' self.terribleNamedMethod = 'of a programmer i will not disclose' j = jelle() shows the proper docstring al'right -- http://mail.python.org/mailman/listinfo/python-list
Re: are docstrings for variables a bad idea?
class GeographicCoordinate: def __init__ (self, lat, long): self.lat = lat "Latitude in degrees (positive North), per WGS84" self.long = long "Longitude in degrees (positive West), per WGS84" Thanks for your example Roy, that illustrates well what I'm after: self.lat = lat "ellipsoid reference: WGS84\nGRS 80 no longer supported" It does exactly what its intended to do: i had no clue what the World Geodetic System and would have asserted my input with a GRS80_2_WGS84 function Little notes to avoid major mistakes. class landClimateOrbiter(NASA): self.speed = self.unit * x Just imagine 'feet' would have popped up when typing self.unit -- http://mail.python.org/mailman/listinfo/python-list
Re: are docstrings for variables a bad idea?
Hi Michele, Thanks for pointing that out, cool! I would argue -even- that is too much programming effort. Like method docstring, variables docstrings should be effortless to write. -- http://mail.python.org/mailman/listinfo/python-list
group several methods under a attribute
Hi, I'm working on a pretty large class and I'd like to group several methods under a attribute. Its not convenient to chop up the class in several smaller classes, nor would mixins really solve the issue. So, what is a pythonic way of grouping several methods under a attribute? Many thanks in advance, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: group several methods under a attribute
> Whatever it is, you should find a better way instead of cramming > everything into a single class. That smells of the God Object > antipattern (http://en.wikipedia.org/wiki/God_object). Thanks Gerard, I'll take your advice. -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: group several methods under a attribute
Hi Aaron, Thanks a lot for your suggestions. I wasnt familiar with the __get__ magic, which seems interesting. So, finally it seems that the cleanest pattern is: class ClsA( object ): def __init__( self, other ): self.inst= other def submethA( self, arg ): print( 'submethA %r, instance %r'% ( arg, self.inst ) ) class ClsB( object ): def methA( self, arg ): self.A= ClsA( self ) print( 'methA %r'% arg ) b= ClsB( ) b.methA( 'this' ) b.A.submethA( 'that' ) Many thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
pypi category
Hi, Would someone be able to inform me how a category can be added to the pypy list of categories? I'd like to add a CAD & Geometry category. ( I develop PythonOCC, wrappers for the OpenCASCADE CAD kernel, which is why ) Thanks! -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: pypi category
The pypi list of categories, sorry... -- http://mail.python.org/mailman/listinfo/python-list
Re: Color Segmentation w/ PIL?
You might be interested in the ndimage module of scipy: http://www.scipy.org/SciPyPackages/Ndimage If you need a very serious image processing framework, ITK is might be very interesting: http://www.itk.org/ If so, have a look at the more Pythonic interface developed for it: www.insight-journal.org/ .../1926/188/2/WrapITK_-_Enhanced_languages_support_for_the_Insight_Toolkit.pdf Cheers, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: shouldn't 'string'.find('ugh') return 0, not -1 ?
> > What's your point? :/ that of making sure before you post and cause public emberassement? -- http://mail.python.org/mailman/listinfo/python-list
Re: shouldn't 'string'.find('ugh') return 0, not -1 ?
There is a subtle point though.
If the substring is not found '_'.find(' '), will return -1
Semanticly, I was expecting the that if the substring was not found, the
conditional statement would not be found.
However, python evaluates -1 to True, so that is what I do find confusing.
So, I was arguing that '_'.find(' ') might return 0, however that is
obviously ambigious, since 0 might be an index as well.
So, perhaps I should rephrase and ask, why if -1 evaluates to True?
I think that's pretty ugly...
cheers,
-jelle
--
http://mail.python.org/mailman/listinfo/python-list
shouldn't 'string'.find('ugh') return 0, not -1 ?
Hi Tim,
Well, I this is another idiom in itself, right?
Your checking if something is part of an iterable.
I'm checking truth before entering a conditional expression.
The latter is considered to be pythonic, right?
-jelle
On 10/31/07, Tim Chase <[EMAIL PROTECTED]> wrote:
>
> > if I check a string for for a substring, and this substring isn't found,
> > should't the .find method return 0 rather than -1?
> > this breaks the
> >
> > if check.find('something'):
> > do(somethingElse)
> >
> > idiom, which is a bit of a pity I think.
>
> That idiom is spelled:
>
> if 'something' in check:
> do(somethingElse)
>
> Unless you really do need to start at a particular offset where
> you use the additional parameters of find(), such as
> find('something', 3, 42). In that case, you can slice your target:
>
> if 'something' in check[3:42]:
>do(somethingElse)
>
> The above is untested, so check for fencepost errors, but the
> theory holds.
>
> So pretty much, I'd never consider using find() :)
>
> -tkc
>
>
>
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Re: shouldn't 'string'.find('ugh') return 0, not -1 ?
> The statement that you want to test the truth of is s.find(q) >= 0. In
> other words, you want to see that the substring was found at a valid
> (non-negative) location. As someone else pointed out, it would make more
> sense to use None instead of -1.
I agree, that would be nice.
You still couldn't use `if s.find(q):` because you'd get a false result
> for a substring found at the beginning of the string, but the return value
> would make more intuitive sense.
I'm sorry, but is that so?
>>>None == 0
False
Since the start of the string is indicated by 0 and not None, that should
work, right?
Witness also the problem of actually using the result of find:
>
> s[s.find(q)]
>
> will yield a valid part of the string (the last character) when q is not
> found. If it evaluated to none, you'd get a respectable TypeError instead.
>
> But you still wouldn't--and never will--be able to say `if s.find(q)`,
> because valid array indices can be either true or false.
Yes, but that is the issue here. If the substring is not found, still find()
returns -1, which is a valid indice.
That I think is ugly. I can't think of a case where it would be prefereble
to have find() return -1 rather than None.
Formally speaking, -1 is an ambigious answer, since a perfectly valid
indice.
the '_'.find(' ') might actually make a nice idiom while parsing for
ignoring irrelevant lines, and processing lines that are of interest in the
conditional expression.
Cheers,
-jelle
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Re: shouldn't 'string'.find('ugh') return 0, not -1 ?
Thanks for your in-depth explanation Tim.
Which is impossible to disagree with!
On 10/31/07, Tim Chase <[EMAIL PROTECTED]> wrote:
>
> > Well, I this is another idiom in itself, right?
> > Your checking if something is part of an iterable.
> > I'm checking truth before entering a conditional expression.
>
> I'm not sure I follow. I simply replaced your
>
> if check.find('something')
>
> with
>
> if 'something' in check:
>
> which (1) is more readable (2) is more pythonic (especially as I
> understand that find() is going away), and (3) works like I
> understand you want from your description.
>
> For strings, they're the same behavior. However, it also works
> for testing membership in other container classes (sets, lists,
> tuples, dicts, etc).
>
> Your original code's behavior would be analog to
>
> if not check.startswith('something')
>
> which is not at all what I think you meant. This
> misinterpretation alone is reason enough to give the find()
> method the boot.
>
> > The latter is considered to be pythonic, right?
>
> Clarity is pythonic. The find() call returns an offset, or -1 if
> not found (because the beginning-of-string is offset=0). It
> would also make sense if this returned None instead of -1.
> Either way, find() should be used for returning index values. If
> you're testing for the presence of a substring, use the
>
> if 'something' in check:
>
> to do the test. And as for the start/end parameters to find,
> they are interpreted as slice endpoints, so
>
> if check.find('something', start) != -1:
>
> would be the same as
>
> if 'something' in check[start:]:
>
> and
>
> if check.find('something', start, end) != -1:
>
> would be the same as
>
> if 'something' in check[start:end]:
>
> both of which are far more readable than their find() variants.
>
> Hope this helps clarify,
>
> -tkc
>
>
>
>
>
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Re: Python 3D CAD -- need collaborators, or just brave souls :)
Hi Josh, > http://www.pythonocc.org/ However, I'm > not entirely clear on the license for this so that might be an issue. We're using a French license for the moment, but will move to something more standard soon. PythonOCC ( the current SVN version ) wraps 85% of the OpenCASCADE kernel. Consider that complete, since there are a bunch of modules are obsolete ( WOK, drawing ). (Binaries are supplied for win32, linux & osx.) We're starting to work on a high level API, so this is a wonderful moment to jump on. -jelle -- http://mail.python.org/mailman/listinfo/python-list
Can't override class |__new__
Hi, I'm working with a C++ module ( CGAL, comp.geom. with exact arithmic ) and am having troubles finding a way to override how the modules returns objects. What I'm trying to do is to extend the Facet class, but when I try to use my version of the class, the parent class is still being returned import CGAL CGAL.Facet = OtherFacet CGAL.Polyhedron.Facet = OtherFacet p = CGAL.Polyhedron_3() p.make_triangle() for f in p.facets: print f # Here I was expecting a OtherFacet object Is there a way of getting around this, or is this behaviour hardcoded in the C++ module? Can I perhaps alter it using the new module or __new__ method? Many thanks in advance, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Can't override class |__new__
Hi Aaron, Thanks so much for your feedback. > Regardless of CGAL's dictionary, it instantiates a Facet. True, when I add attributes to it, they are disregarded when looping through the facets later on. > Depending on the details, you may need only to cut-and-paste your own > 'make_triangle' function, and just replace the line I showed. Ok, thanks so much for pointing me in the right direction. I suppose there is no way to fix this on the interpreter level... Thanks so much for your help in finding this bug! > Do you have a link to the source for CGAL? In fact I'm using the python wrappers of CGAL. Here's a link to the Polyhedron module. In fact, I can add methods and attributes to this class, just the Facet instances do not behave as expected. https://gforge.inria.fr/plugins/scmsvn/viewcvs.php/trunk/cgal- python/bindings/Polyhedron/Py_Polyhedron_3.cpp?rev=167&root =cgal-python&view=markup Again, thanks for you help, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Can't override class |__new__
> > CGAL.Facet = OtherFacet > > CGAL.Polyhedron.Facet = OtherFacet > > p = CGAL.Polyhedron_3() > You're not creating Facet object here, not even Polyhedron.Facet. Right, which is not the point; I'm trying to override the Facet, a topological entity of which a Polyhedron is composed of . ( vertex -> halfedge -> facet -> polyhedron ) > I think so. External module written in C/C++ is often statically linked. I'm sorry, but I don't follow you; what has linking to do with changing the behaviour of the compiled module? Thanks, -jelle -- http://mail.python.org/mailman/listinfo/python-list
Re: Can't override class |__new__
> Aaron explained it better than I did. Basically the C/C++ module uses > C/C++ version of Facet class directly without consulting python > interpreter, this is what I meant by static linking. Thanks so much for the explanation Lie, I understood it fully now. Thanks again, -jelle -- http://mail.python.org/mailman/listinfo/python-list
SimpleXMLRPCServer and creating a new object on for each new client request.
Hi list,
My goals is to have concurrent and separated client sessions using xmlrpc.
Initially my though was that SimpleXMLRPCServer was able to create a new
object instance for each incoming request.
But this doesn't appear to be the case, unless I'm overlooking something,
if so please point me out.
Concider following simplified code
#!/usr/bin/python
from SimpleXMLRPCServer import SimpleXMLRPCServer
from SimpleXMLRPCServer import SimpleXMLRPCRequestHandler
import random
# Restrict to a particular path.
class RequestHandler(SimpleXMLRPCRequestHandler):
rpc_paths = ('/RPC2',)
# Create a simple example class
class Randomizer:
def __init__(self):
self.random=random.randrange(0,10)
def show_random(self):
return self.random
# Create server
server = SimpleXMLRPCServer(("localhost",
8000),requestHandler=RequestHandler,allow_none=1)
server.register_introspection_functions()
server.register_instance(Randomizer())
server.serve_forever()
I start python interactively:
>>> import xmlrpclib
>>> session1=xmlrpclib.ServerProxy('http://localhost:8000')
>>> session2=xmlrpclib.ServerProxy('http://localhost:8000')
>>> print session1.show_random()
13930
>>> print session2.show_random()
13930
>>>
I though that session1 and session2 would be 2 different Randomizer objects
each having a different result for self.random
But as the example shows this is not the case.
How can I solve this?
Thanks
Jelle
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CAD -> FEM | writing FEM meshes in abacus format || pythonOCC
Hi, I'm wondering whether someone has experience / code / pointers on how to write FEM meshes to Abacus ( Simulia, whatever ). We're making good progress at the pythonOCC(.org) project in coupling CAD & FEM and a next step would be to plug the generates meshes into a major FEM solver such as abaqus. I'm aware abaqus has a python module which is great, but is off limits. Any ideas / references are much appreaciated! -jelle -- http://mail.python.org/mailman/listinfo/python-list
python regex "negative lookahead assertions" problems
Hi List,
I'm trying to match lines in python using the re module.
The end goal is to have a regex which enables me to skip lines which have ok
and warning in it.
But for some reason I can't get negative lookaheads working, the way it's
explained in "http://docs.python.org/library/re.html";.
Consider this example:
Python 2.6.4 (r264:75706, Nov 2 2009, 14:38:03)
[GCC 4.4.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> line='2009-11-22 12:15:441 lmqkjsfmlqshvquhsudfhqf qlsfh qsduidfhqlsiufh
>>> qlsiuf qldsfhqlsifhqlius dfh warning qlsfj lqshf lqsuhf lqksjfhqisudfh
>>> qiusdfhq iusfh'
>>> re.match('.*(?!warning)',line)
<_sre.SRE_Match object at 0xb75b1598>
I would expect that this would NOT match as it's a negative lookahead and
warning is in the string.
Thanks,
--
Jelle Smet
http://www.smetj.net
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os.spawnv & stdin trouble
##I know I should be using 2.4 and os.Popen,
I know, I know…
##However, since most modules I need, I’m using 2.3
for this script
I’m having troubles executing a shell script.
The thing is that I’m produing
material and geometry files that need to be compiled to a binary description (for
those familiar to Radiance, oconv)
The trouble I’m having is that when python goes
through my loop, files are overwritten before os.system
was able to process these! (who ways complaining
python is slow, well I’m not!! ;-) So the obvious thing to do is to swap os.system for os.spawnv.
Here’s where I run into trouble.
In my os.system version, I’m
perfectly able to pipe into another file, since the process has no real
connection to python whatsoever.
Would someone be able to explain me how to do this, all the
tools I’m using for this script are unix-like
tools and heavily rely on piping.
program =
'xform.exe'
path =
'c:\Radiance\bin\'
args = ['-t 0 8
0', 'wall0.rad', '>', 'wall0.TRANS.rad']
os.spawnv(os.P_WAIT, path, ('xform', args))
here’s the cmd error message:
xform: cannot
find file ">"
##for your info I’m on win/xp,
python 2.3.4
Cheers,
Jelle.
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os.spawn & stdOUT trouble
Yikes, how painful, I meant stdOUT > trouble instead of stdin... Awefully sorry Cheers, Jelle ##thanks for pointing that out Denis! -- http://mail.python.org/mailman/listinfo/python-list
OCAMl a more natural extension language for python?
After reading about extending python with C/Fortran in the excellent Python Scripting for Computational Science book by Hans Langtangen, I'm wondering whether there's not a more pythonic way of extending python. And frankly I think there is: OCAML Fortunately there is already a project up and running allowing you to extend python with OCAMl: http://pycaml.sourceforge.net/ Since I haven't got actual experience programming CAML I'd like to speculate that OCAML would be a very pythonic way of extending python: its open-source, object oriented, as fast as C, and ! garbage collecting! Would making an effort integrating python & CAML not be very worthwhile? I think an effort such as Joe Strouts python2c would be more relevant to a language as CAMl since its conceptually more closer to python (how could you automate programming memory allocation for instance) So my question is: wouldn't there be some serious synergy in bringing python & CAML closer together? ##of course this is speculation, I'm not informed well ##enough to make an educated guess Interested in hearing your thoughts about this matter! Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
RE: OCAMl a more natural extension language for python?
H. Not familiar with erlang at all... > Subject: Re: OCAMl a more natural extension language for python? > > Hi ! > > OCAML is very complementary at Python : > > unreadable vs readable That's depending on how you compare; I find OCAML quite readable compared to C / Fortran > functionnel vs procedural/POO/etc. OCAML is not a true functional language, its also OO > compiled vs interpreted (or compil JIT) > very fast vs mean velocity What I'm looking for! > hard to learn vs easy to easy to learn Is it in comparison to C? > Yes, OCAML is very complementary, too much, much too, complementary at > Python... > > But, C is not complementary to Python (in the same state of mind). So some additional arguments to the hypotheses of OCAMl being a natural extension language to Python? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
python & iges (nurbs file format)
Is anyone aware of a module allowing you to read / write .iges data? Currently I’m trying to figure a way of writing out my nurbs data generated in python, but if such a package exists, that would be great, haven’t been able to find anything so far… Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
building extensions: ming & python mathlink for win32
Have been trying to build python extensions from the C libs ming & mathlink. I have been able to produce a .pyd object after studying Mike Fletchers excellent: http://www.vrplumber.com/programming/mstoolkit/ which is a terrific tutorial for anyone trying to compile .pyd on win32! Building mathlink (communicating with mathematica from python!) was semi successful in the sense that it did build a .pyd, Semi, since importing it gave: >>> import mathlink Fatal Python error: Error initializing mathlink extension module This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. Has anyone been able to compile this extension for python? Same thing goes for Ming (c lib for compiling flas .swf files), such a pity no disutils script is included in this very powerful library! ##if you succeeded to build this, please consider sharing it with me! (2.3 is fine as well!) What struck me while trying to compile is that instead of the Active Python 2.4 version I was running I downloaded and installed the python.org version (as recommended by Fletcher), and while launching it, I stated ActivePython 2.4 Build 243 (ActiveState Corp.) based on Python 2.4 HUH! WHAT! No actual difference between the python.org & activestate version??? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
compiling ming on win32/python 2.3
I wonder whether anyone on this list has been able to compile the ming .swf output library successfully on win32/python2.3? I have quite some trouble trying to compile these kind of libraries, maybe you could point me to a good starters tutorial on this? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
python & nurbs
Is anyone aware of a python nurbs module? So far I found Runar Tenfjord's effort, which is quite interesting: http://runten.tripod.com/NURBS/ But in the end doesn't really meet my needs. Any suggestions? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
RE: python & nurbs
> Hint to get a useful answer: Define your needs. Display in 3D (want to > use them to define and display geometry)? Numeric analysis (writing > some sort of CAD or automation system)? Modeling system (want some way > to interactively define them)? I wish I could give you a well defined answer to this. At the moment I'm fed up by the limited capabilities of mainstream cad modelers such as Rhino. I'm interested in using for instance Gaussian curvature functions to model geometry. More interested in computing rather than drawing. The problem so far is that either you computer or draw. I'm looking for something that would do both. For instance I've been studying to script Rhino (using COM) which looks promising, but since Rhino isn't a parametric modeler, it wont meet my need. Topsolid looks like an option. Too bad blender doesn't have any cad/parametric capabilities, that could have been a sweet option > OpenGLContext has a set of NURBs nodes modeled after the VRML97 NURBs > extension, though they don't see all that much usage. I would imagine > some of the other retained-mode systems have them as well. > > My collection of links to retained-mode engines is here: > http://www.vrplumber.com/py3d.py?category=retained Col! I've had a few look arounds your site, its GREAT!!! Best python/graphic portal I've seen so far! Thank you!!! > If you want something for doing numeric analysis of NURBs, don't know > where you'd find it. > Many 3D modelers will let you create nurbs surfaces. IIRC Rhino was the > pre-eminent NURBs-focused modeler a few years ago. Rhino has been my tool of trade for quite some time. Time to move over to an environment to profoundly supports python scripting! My feeling is that Rhino is getting out of date rapidly by the lack of parametric modeling. But let me stop discussing this soft on this list... Thanks for your feedback so far! -- http://mail.python.org/mailman/listinfo/python-list
RE: python & nurbs
> Have you looked at Blender (http://www.blender3d.com)?? Blender seems very promising, its python support is exactly what I'm looking for, but it lacks the cad/parametric capabilities I'm looking for. -- http://mail.python.org/mailman/listinfo/python-list
Modules and Namespaces
##I'm sorry to stir up such a well discussed topic yet again, but namespaces are a point of confusion to me... I took the effort of organizing my Python code (scripting a cad program calles Rhino) in well defined classes, which would be a terrific thing if I didn't got stuck in namespace issues. I have a module that launches the application I'm scripting via win32com; rhino.load from rhino import load RS = load.RS So the application, with all its methods are now available through the RS (RhinoScript) object from rhino import SRF # is where things get stuck The RS object is the application scripted via COM, where all its method reside. In my module, SRF, I'm not importing anything, though it refers to the RS object all the time. Such as: class srfBase: '''Base class inherited by the srf* classes, binding general Rhino surface functionality to a particular surface generation method''' def __init__(self): self.id = 'self.id srfBase' pass def isBrep(self): return RS.IsBrep(self.id) def isPointInSurface(self, coord): return RS.IsPointInSurface(self.id, coord) How do I make the RS object available to the imported SRF module, such that my module code and program code both refer to RS as the application object being scripted? Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
genetic algorithms
Could anyone recommend me a genetic algorithm package? So far I have found a few, such as GAS, pyGP, Genetic, and of course scipy.ga My problem is that most of the development of these packages seems to be stalled, or that in scipy.ga's case, the module seems huge and somewhat overly complicated. Could someone recommend me a module, which is still being developed, somewhat more concurrent than the stuff I'm finding? Any recommendations, since most of these modules seem to be more projects developed in sake of grasping GA's rather than actually using these ;-) Cheers, Jelle. -- http://mail.python.org/mailman/listinfo/python-list
