[issue20496] function definition tutorial encourages bad practice
New submission from Alan Isaac: Section 4.6 of the tutorial introduces function definition: http://docs.python.org/3/tutorial/controlflow.html#defining-functions The first example defines a function that *prints* a Fibonacci series. A basic mistake made by students new to programming is to use a function to print values rather than to return them. In this sense, the example encourages bad practice and misses an opportunity to instruct. Since they have already met lists in Section 3, I suggest that returning a list of the values and then printing the list would enhance the tutorial. -- assignee: docs@python components: Documentation messages: 210077 nosy: aisaac, docs@python priority: normal severity: normal status: open title: function definition tutorial encourages bad practice type: enhancement ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue20496 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18844] allow weights in random.choice
New submission from Alan Isaac: The need for weighted random choices is so common that it is addressed as a common task in the docs: http://docs.python.org/dev/library/random.html This enhancement request is to add an optional argument to random.choice, which must be a sequence of non-negative numbers (the weights) having the same length as the main argument. -- messages: 196229 nosy: aisaac priority: normal severity: normal status: open title: allow weights in random.choice type: enhancement ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue18844 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue11023] pep 227 missing text
Alan Isaac alan.is...@gmail.com added the comment: Bear with my confusion about your response. Are you saying that CPython documentation bugs cannot be submitted here, or that this does not constitute a CPython documentation bug? I assume the latter. But then, can you tell me where to find the correct CPython documentation after I read the following quote from PEP 277? http://www.python.org/dev/peps/pep-0227/ Implementation XXX Jeremy, is this still the case? The implementation for C Python uses flat closures [1]. In case you might care about a user confusion ... Your reply left me puzzled that PEPs that have reached the standards track would not be considered part of the CPython documentation distribution. Thank you, Alan Isaac -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue11023 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue11023] pep 227 missing text
New submission from Alan Isaac alan.is...@gmail.com: In PEP 227 missing text is marked with XXX. Most of this is just calls for examples and elaboration. However under the Implementation section XXX marks a substantive question about the documentation. Fixing this may be low priority, but a tracker search suggested it is currently not even being tracked ... -- assignee: docs@python components: Documentation messages: 127184 nosy: aisaac, docs@python priority: normal severity: normal status: open title: pep 227 missing text type: feature request ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue11023 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5716] Overzealous deprecation of BaseException.message
Alan Isaac alan.is...@gmail.com added the comment: FYI a patch has been committed that should fix this. For discussion see http://bugs.python.org/issue6844 -- nosy: +aisaac ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue5716 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6844] BaseException DeprecationError raises inappropriately
Alan Isaac alan.is...@gmail.com added the comment: I hope it is not too annoying to link these ... I asked thhis of Jean-Paul but now I'll ask it of George. Since you are working on this, can you see if http://bugs.python.org/issue6108 is related or in any case can be fixed at the same time? Thanks. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6844 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6844] BaseException DeprecationError raises inappropriately
Alan Isaac alan.is...@gmail.com added the comment: Since you are working on this, can you see if http://bugs.python.org/issue6108 is related or in any case can be fixed at the same time? Thanks. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6844 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6844] BaseException DeprecationError raises inappropriately
Alan Isaac alan.is...@gmail.com added the comment: The 'message' attribute itself is deprecated as it didn't exist prior to being introduced in 2.5. That seems to me to be the wrong way to phrase it, and indeed that kind of phrasing implies the current bug. For example, it leads to the incorrect statement that The 'message' attribute ... didn't exist prior to being introduced in 2.5. But looking at the docutils and Twisted code bases, to take two examples, tells us that it **did** exist: a slew of instances had this attribute. The correct statement, that BaseException did not initialize a `message` attribute, is an entirely different matter. Imo, deprecating setting and accessing an **instance attribute** is just flat out wrong and grossly violates inheritability promises. As we have seen. I think (?) that what was desired to be deprecated is the combination of - setting a message attribute via BaseException.__init__, AND - accessing an instances message attribute that was set *this way* But in fact the setting cannot really be deprecated because it is implicit: it is something currently done by BaseException, not by the user. So I think (?) the best we can do is look at whether the user initializes BaseException (**not** the derived classes) with a single argument, which is a nonempty string, and then tries to access this as a `message` attribute. Which is why I originally proposed setting a flag when BaseException.__init__ is called and conditioning the deprecation warning on this flag. (E.g., the flag could be set if and only if the user calls BaseException.__init__(instance, string).) In any case, I think Jean-Paul is asking exactly the right question (i.e., just what exactly is being deprecated?). A more careful answer will hopefully lead to less buggy DeprecationWarning. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6844 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue6844] BaseException DeprecationError raises inappropriately
New submission from Alan Isaac alan.is...@gmail.com: In Python 2.6 if I subclass Exception and intialize my instances with a `message` attribute, I get a DeprecationError via BaseException. Of course there is no problem in Py3, because adding a `message` attribute to instances of a subclass is in fact **not** a problem and will **not** be disallowed. I.e., the DeprecationError is raised incorrectly in Python 2.6. I am not sure how to raise a DeprecationError *only* in the correct cases, but certainly the current behavior can be much improved. As a crude example, if the `args` passed to BaseException has length 0, then a flag could be set not to raise this DeprecationError. Even if not perfect, this would be **much** better than the current behavior, since it is common practice not to pass the subclass's initialization arguments on to Exception.__init__. This behavior can be expected to affect entire libraries and therefore should be fixed. (Eg., it affects docutils.) I.e., change the name of your variable is the wrong answer to this bug report. -- components: Interpreter Core messages: 92281 nosy: aisaac severity: normal status: open title: BaseException DeprecationError raises inappropriately type: behavior versions: Python 2.6 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue6844 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
Re: function factory question: embed current values of object attributes
Terry Reedy wrote: You are now describing a function closure. Here is an example that might help. It does. Thanks, Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: function factory question: embed current values of object attributes
Gabriel Genellina wrote: If you want a frozen function (that is, a function already set-up with the parameters taken from the current values of x.a, x.b) use functools.partial: OK, that's also a nice idea. Thanks! Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: is it possible to add a property to an instance?
Darren Dale wrote to GHUM: Sorry, that's an attribute, not a property. This is a question about terminology. In contrast to Darren's recommended usage, I have run into the following. If hasattr(x,'a') is True, for instance object `x`, then `a` is an attribute of `x`. Attributes are data attributes or callable attributes. Data attributes are variables or properties. Callable attributes are usually method attributes. This seemed about right to me, but a better (or official) taxonomy would be welcome. Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
function factory question: embed current values of object attributes
I have a class `X` where many parameters are set at instance initialization. The parameter values of an instance `x` generally remain unchanged, but is there way to communicate to a method that it depends only on the initial values of these parameters (and does not need to worry about any changes)? The behavior of method `m` depends on these parameter values. It turns out `m` gets called a lot, which means that the pameter values are accessed over and over (self.p0, self.p1, etc). I would like to manufacture a function equivalent to the method that simply uses fixed values (the values at the time it is manufactured). I do not care if this function is attached to `x` or not. I have a feeling that I am turning something simple into something complex, perhaps for lack of an afternoon coffee or lack of CS training. Suggestions appreciated. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Python with Ecmascript
NJSModule? http://en.wikipedia.org/wiki/NJS Daniel Fetchinson wrote: This seems to be very good indeed. Just downloaded njs but the only njsmodule version I could find was for python 2.1. Does anyone have a recent copy? 1. You might ask here: http://lists.njs-javascript.org/cgi-bin/mailman/listinfo/users 2. Did you try to compile it? Is there anything obviously 2.5 incompatible? Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Python with Ecmascript
Daniel Fetchinson wrote: Is there a way to do similar things on linux? NJSModule? http://en.wikipedia.org/wiki/NJS Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Market simulations with Python
xamdam wrote: I am interested in market simulation with Python, simulating buyers and sellers arriving with goods at random times. I looked at SimPy, it's pretty nice, but all the examples are around congestion problems. Should I a) dig deeper b) write something from scratch c) look at another library? You could use SimPy. Also see: http://gnosis.cx/publish/programming/charming_python_b10.html http://www.mech.kuleuven.be/lce2006/147.pdf If you plan to share you efforts, please post updates here. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Dynamically naming objects.
On Jun 7, 1:20 pm, Hans Nowak [user() for i in range(n)] Kalibr wrote: or does it somehow work? how would I address them if they all have the name 'u'? users = list(User() for i in range(n)) for user in users: user.do_something() hth, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: parser recommendation
One other possibility: SimpleParse (for speed). URL:http://simpleparse.sourceforge.net/ It is very nice. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Ideas for master's thesis
Filip Gruszczyński wrote: I am student of CS at the University of Warsaw, currently 4th year. I am attending Object Oriented Programming seminar and it is about time, I started looking for an idea of my master's degree project. As I like Python very much, I would like to do something with this language, yet I don't know if there are any needs/science fields, that could be used as a basis for a thesis. Therefore I would like to ask, if there is any way to access any person involved in development, who would help me find some field that need to be developed/researched (rather the first one) and would be close enough to the OOP, so I could present it to a mentor (he is cool with doing something for OSS community). There has been discussion of replacing/supplementing the NumPy matrix class. The newmatrix class would still subclass ndarray but would handle indexing differently. I am confident that you could get a lot of guidance on the NumPy list if you were interested in taking this on. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: should I put old or new style classes in my book?
This thread raises two questions for me. 1. I take it from this thread that in Python 3 the following are equivalent: class Test: pass class Test(object): pass Is that correct, and if so, where is it stated explicitly? (I know about the all classes are new style classes statement.) 2. I take it from this thread that in Python 2.2+ if I put the following at the top of a module :: __metaclass__ = type then all the classes defined in that module will be newstyle classes. Is that correct? Somehow I did not grok that from URL:http://docs.python.org/ref/metaclasses.html but it seems right. Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: make a string a list
Nikhil wrote: or a string iterable ? How can I do that. I have lots of '\r\n' characters in the string which I think can be easier if it were made into a list and I can easily see if the required value (its a numeral) is present in it or not after some position or after some characters' position. Why dont the ``find`` or ``index`` methods work for you? http://docs.python.org/lib/string-methods.html Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: code of a function
Anand Patil wrote: If you're using IPython, you can do svd?? . http://www.scipy.org/doc/numpy_api_docs/numpy.linalg.linalg.html hth, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: observer pattern (notification chain synchronization)
J. Cliff Dyer wrote: looks like a good approach to me OK, thanks. Another approach is to begin with a set of stocks and remove them as they report. You can then trigger a report with the empty set instead of repeatedly calling ``all``. After a report the set can be refilled. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
observer pattern (notification chain synchronization)
A question related to the observer pattern... Suppose I have a variant: there are stocks, mutual funds, and investors. Let us say that funds are observers for multiple stocks, and investors are observers for funds. Once a month all stocks notify their observing funds of their end-of-month price, and *then* all fund to notify their observing investors of their end-of-month investment value. What is a good way to enforce this timing? (I.e., a fund should not notify an its investors until all stocks have reported.) Here is one way: - for each fund, create a ``reportreceived`` dict that maps stocks to booleans (initially False) - as each stock notifies its funds, the fund changes False to True and checks ``all(reportreceived.values())`` to determine whether it is ok to notify investors. - When it is ok, the fund notifies investors and resets all the ``reportreceived`` values. Is this sensible enough? What are standard and better ways? Thank you, Alan Isaac PS I am drawing on the description of the observer pattern at URL:http://www.dofactory.com/Patterns/PatternObserver.aspx#_self1 The real world aspects are just to add some concreteness. -- http://mail.python.org/mailman/listinfo/python-list
observer pattern question #1 (reference to subject)
I have two questions about the observer pattern in Python. This is question #1. (I'll put the other is a separate post.) Here is a standard example of the observer pattern in Python: http://en.wikipedia.org/wiki/Observer_pattern Contrast with this rather standard discussion: http://www.dofactory.com/Patterns/PatternObserver.aspx#_self1 The difference I am focusing on is that in the latter, the observer (investor) maintains a reference to the subject (stock). (Many questions can be raised of course: see the discussion at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/131499). Is anything lost by not maintaining this reference (other than error checking ...)? If I feel the observer needs access to the subject, what is wrong with just having the subject pass itself as part of the notification? Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
observer pattern question #2 (notification chain)
I have two questions about the observer pattern in Python. This is question #2. (I'll put the other is a separate post.) Consider this standard example of the observer pattern in Python: URL:http://en.wikipedia.org/wiki/Observer_pattern Now suppose I have a variant. (I am not a programmer, so this may be a separate related pattern.) To make it a little concrete and relate it to the discussion at URL:http://www.dofactory.com/Patterns/PatternObserver.aspx#_self1, suppose there are stocks, mutual funds, and investors. Let us say that funds are observers for stocks, and investors are observers for funds. Once a month I want all stocks to notify their observing funds of their end-of-month price, and *then* all fund to notify their observing investors of their end-of-month investment value. I see a couple differences from the standard pattern referenced above, and one problem. Differences: - observer/subject linked hierarchy (funds are both observers and subjects) - many-many relation (a fund is an observer of many stocks) I think (?) these differences are inessential, but the second does create the following problem: if I do not want a fund to notify an its investors until all stocks have reported, what is the best way to determine the last report in event? Here is one way: create a ``reportreceived`` dict that maps stocks to True or False, and after each stock notification change False to True and check ``all(reportreceived.values())`` to determine whether it is ok to notify investors. When it is ok, then notify investors and reset all the ``reportreceived`` values. This is meant to be a general description so please do not focus on the real world aspects, which are only for illustration. Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: observer pattern question #1 (reference to subject)
Alan Isaac [EMAIL PROTECTED] writes: Is anything lost by not maintaining this reference (other than error checking ...)? If I feel the observer needs access to the subject, what is wrong with just having the subject pass itself as part of the notification? Ville M. Vainio wrote: It reduces the number of places the observer can be called from, because now the event source is part of the function signature. If you omit the event source in the signature, you gain looser coupling - it's the observer business to create the dependency. As I said, I'm not a programmer, and perhaps as a result, I have questions about both of your points. I'll stick with the stock example, since it is concrete. Note that the observor/listener in the example at URL:http://en.wikipedia.org/wiki/Observer_pattern does not create a reference to the subject. So in this context I take you to be saying something like the following: OK, here's the pattern, now your listener wants to know the event source, do not ask something new the subject to respond to that need. That is unnecessary coupling. Instead, just rewrite your listener to maintain a reference to the subject. Do I have that right? It seems to me that this response begs the question. That is, an appropriate reply seems to be: here is a related pattern, call it observer2. In the observer2 pattern, the subject has a getState method and always passes itself when it notifies the observer. Now: in what sense does this require closer coupling? Also, consider the situation where you want all investors to refresh their idea about stock prices (because of, short network failure). It's easy to run through a list of them and call update() for everybody, while it's not so easy to find out what stock the investor is observing (that's the investors business!) and pass that object to the investor in the call. I seem to be missing your point here. Let's keep using the stock/investor example. When the network comes up, each stock should notifies everyone in its list of listeners. It either passes itself or does not. In either case, the investor took care of hir side of the business by registering as a listener. If the stock does not notify all its registered investors, it is breaking its contract. So, what is the problem? Or to put it a different way, your suggestion that the investors should have to *pull* this information from the stocks seems out of step with the observer pattern, where the stocks should be pushing this information to the investor. Again, talk of stocks and investors is just a convenient short hand for discussing the observer pattern. I do not care about stocks/investors more than other applications. Are these school questions btw? No, sorry. But I still appreciate the feedback. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: observer pattern question #1 (reference to subject)
Ville M. Vainio wrote: in case of stocks, you are probably monitoring several stock objects, so the stock should probably pass itself to the observer OK. This is related to my question #2 (in a separate thread), where I'd also appreciate your comments. analogous to a typical UI scenario where you have several widgets forwarding events to one big observer - and they *do* provide the event source and event type. That is a helpful comparison. All in all, though, the right solution should be obvious from the problem at hand. For CS types, maybe. The rest of us are just trying to get things done without as much background and context. Thanks, Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: python vs. grep
Anton Slesarev wrote: I've read great paper about generators: http://www.dabeaz.com/generators/index.html Author say that it's easy to write analog of common linux tools such as awk,grep etc. He say that performance could be even better. But I have some problem with writing performance grep analog. https://svn.enthought.com/svn/sandbox/grin/trunk/ hth, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Help me on function definition
aeneng wrote: WHAT IS WRONG WITH MY CODE? def cross(u,v) Missing colon. hth, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: method to create class property
Diez B. Roggisch wrote: In python 3.0, there will be an even nicer way - propset: @property def foo(self): return self._foo @propset def foo(self, value): self._value = value Isn't that:: @propset(foo) def foo(self, value): self._value = value Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: no more comparisons
Dan Bishop wrote: def cmp_key(cmp_fn): class CmpWrapper(object): def __init__(self, obj): self.obj = obj def __cmp__(self, other): return cmp_fn(self.obj, other.obj) return CmpWrapper Apparently I'm overlooking something obvious ... how is this supposed to work if __cmp__ is no longer being called? (Which was my understanding.) Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: no more comparisons
Dan Bishop wrote: def cmp_key(cmp_fn): class CmpWrapper(object): def __init__(self, obj): self.obj = obj def __cmp__(self, other): return cmp_fn(self.obj, other.obj) return CmpWrapper On Mar 13, 12:38 pm, Alan Isaac wrote: how is this supposed to work if __cmp__ is no longer being called? (Which was my understanding.) Carl Banks wrote: It won't. In Python 3.0 you'd have to write this class in terms of rich comparisons (__lt__, __gt__, etc.). Exactly. So something simple (define an anonymous function) has become a bit of a pain. On the other hand, I've looked through my extant code and have not found a use of ``cmp`` that I cannot work around. So maybe this is not as bad as I feared. What are some use cases that will clearly be harder (i.e., at least require a slightly elaborate wrapper) after this change? Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: no more comparisons
Mark Dickinson wrote: Sorting tuples, where the second item in the tuple should have the opposite ordering to the first is going to be a bit of a pain. Or even worse, where the ordering of the second item depends on the value of the first item in the tuple. This is like some examples where I had used cmp, but if I understand correctly I think it is not a problem. For example, suppose that (for whatever contrived reason) you're representing integers in (sign, magnitude) format by tuples (s, i), where s = 0 or 1 (0 for positive, 1 for negative) and i is a string representing the absolute value of the integer. So Does this do it? :: key= lambda x: (-x[1],int(x2)) Here I am depending on the lexicographic sorting of tuples. Without that there would be real trouble. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: no more comparisons
Dan Bishop wrote: Even assuming you meant (-x[0], int(x[1])), that sorts negative numbers in the wrong order. You want key = lambda x: (-1 if x[0] else 1) * int(x[1]) Sorry, was speed typing (very badly) and the question actually had two different problem descriptions. As you suggest, what I meant was:: key= lambda x: (-x[0], int(x[1])) which was meant to address: Sorting tuples, where the second item in the tuple should have the opposite ordering to the first is going to be a bit of a pain. But you are quite right, the problem was then specified to numerical order, for which I like your solution. Or even:: key= lambda x: -int(x[1]) if x[0] else int(x[1]) The key point being, if you will, that this use case does not support the idea that relying on ``key`` will be so bad. So, what is a case that is really uncomfortable? Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
no more comparisons
I was surprised to see that comparison is slated for death in Python 3000. For example: http://www.python.org/dev/peps/pep-3100/ list.sort() and builtin.sorted() methods: eliminate cmp parameter [27] [done] But there is a rumor of a PEP to restore comparisons. http://mail.python.org/pipermail/python-3000/2008-January/011764.html Is that going anywhere? Also, what is the core motivation for removing this functionality? Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: no more comparisons
Paul Rubin wrote: The cmp option should not be removed. However, requiring it to be specified as a keyword parameter instead of just passed as an unlabelled arg is fine. Sure; I would have no problem with that. But that is not what is happening. As for Carl's suggestion to use ``key``: this is already possible when it is convenient, but it is not always convenient. (Even aside from memory considerations.) By the way, I even saw mention of even removing the ``cmp`` built-in. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Can't get items out of a set?
Cruxic wrote: people = set( [Person(1, 'Joe'), Person(2, 'Sue')] ) ... p = people.get_equivalent(2) #method doesn't exist as far as I know print p.name #prints Sue def get_equivalent(test, container): for p in container: if p == test: return p hth, Alan Isaac #example (note change in __eq__ to match your case; fix if nec) class Person: def __init__(self, id, name): self.id = id self.name = name def __hash__(self): return self.id def __eq__(self, other): return self.id == other people = set( [Person(1, 'Joe'), Person(2, 'Sue')] ) get_equivalent(2,people) -- http://mail.python.org/mailman/listinfo/python-list
Re: Is it possible to return a variable and use it...?
Nathan Pinno wrote: Is it possible to return a variable and then use it I think you are asking about the ``global`` statement. URL:http://docs.python.org/ref/global.html like the following: Presumably not. ;-) Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: tuples, index method, Python's design
On April 12th, 2007 at 10:05 PM Alan Isaac wrote: The avoidance of tuples, so carefully defended in other terms, is often rooted (I claim) in habits formed from need for list methods like ``index`` and ``count``. Indeed, I predict that Python tuples will eventually have these methods and that these same people will then defend *that* status quo. URL:http://python.org/download/releases/2.6/NEWS.txt - Issue #2025 : Add tuple.count() and tuple.index() methods to comply with the collections.Sequence API. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: tuples, index method, Python's design
Paul Boddie wrote: Here's the tracker item that may have made it happen: http://bugs.python.org/issue1696444 I think you need to thank Raymond Hettinger for championing the cause. ;-) Yes indeed! Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: more pythonic
Paul McGuire wrote: In general, whenever you have: someNewList = [] for smthg in someSequence: if condition(smthg): someNewList.append( elementDerivedFrom(smthg) ) replace it with: someNewList = [ elementDerivedFrom(smthg) for smthg in someSequence if condition(smthg) ] What is the gain? (Real question.) I think the first is often easier to read. Is the second more efficient? Also, I think list comprehensions are often easier to read as equivalent generator expressions: someNewList = list( elementDerivedFrom(smthg) for smthg in someSequence if condition(smthg) ) Tastes vary of course. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Pythons Ladders
Benoit wrote: Give me something to do! Help to improve one of the experimental writers for docutils. IIRC, the ODT writer does not yet support figures and tables. http://www.rexx.com/~dkuhlman/odtwriter.html The rst2wordml writer appears to be getting its features in place, but when I last used it, some tinkering was required. You could work on adding features. http://docutils.sourceforge.net/sandbox/rst2wordml/readme.html If you get good enough a docutils, provide an option to have the number for the note be superscripted, like the note reference can be. fwiw, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: asynchronous alarm
Paul Rubin wrote:
a = Event()
Thread(target=f, args=(a,)).start()
raw_input('hit return when done: ')
a.set()
Simple and elegant.
Thank you.
Alan
--
http://mail.python.org/mailman/listinfo/python-list
asynchronous alarm
Goal: turn off an audible alarm without
terminating the program. For example,
suppose a console program is running::
while True:
sys.stdout.write('\a')
sys.stdout.flush()
time.sleep(0.5)
I want to add code to allow me to turn off
this alarm and then interact with the
program in its new state (which the alarm
alerts me to).
Question: how best to do this mostly simply
in a console application and in a Tkinter application?
I realize this must be a standard problem so that there
is a good standard answer. Here are some naive solutions
that occured to me.
Solution C1 (console): poll keyboard inside the loop.
E.g., URL:http://effbot.org/librarybook/msvcrt.htm
Problem: no platform independent way to do this?
Solution C2 (console): handle KeyboardInterrupt.
An ugly hack. But works fine.
Solution C3 (console): start alarm in one thread
and wait for raw_input. (Should that be in another
thread? It does not seem to matter.)
This seems plausible, but I know nothing about threads
except that nonprogrammers tend to make mistakes
with them, so I hesitate.
Solution G1 (gui): start alarm in a thread but
include a test for a variable that can be set
by a button push? (Sounds plausible etc.)
Solution G2 (gui): start alarm but
somehow let Tkinter listen for an event
without programming any threads. Possible??
Thanks,
Alan
--
http://mail.python.org/mailman/listinfo/python-list
Re: basic output question
John Deas wrote: My problem is that f.read() outputs nothing Since ``open`` did not give you an IOError, you did get a handle to the files, so this suggests that the files you read are empty... Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: find minimum associated values
[EMAIL PROTECTED] wrote: I'd use the first solution. It can be speeded up a bit with a try/except: for k,v in kv: try: if d[k] v: d[k] = v except KeyError: d[k] = v Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: find minimum associated values
Alan Isaac wrote: #sort by id and then value kv_sorted = sorted(kv, key=lambda x: (id(x[0]),x[1])) #groupby: first element in each group is object and its min value d =dict( g.next() for k,g in groupby( kv_sorted, key=lambda x: x[0] ) ) Yes, that appears to be fastest and is pretty easy to read. On average. For the specified problem. ;-) -- http://mail.python.org/mailman/listinfo/python-list
Re: find minimum associated values
Steven Bethard wrote: [3rd approach] Seems pretty enough to me. ;-) I find it most attractive of the lot. But its costs would rise if the number of values per object were large. Anyway, I basically agree. Thanks, Alan -- http://mail.python.org/mailman/listinfo/python-list
find minimum associated values
I have a small set of objects associated with a larger set of values, and I want to map each object to its minimum associated value. The solutions below work, but I would like to see prettier solutions... Thank you, Alan Isaac === import time, random from itertools import groupby from collections import defaultdict class Pass: pass # arbitrary setup keys = [Pass() for i in range(10)]*3 vals = [random.random() for i in range(30)] kv = zip(keys,vals) random.shuffle(kv) #OBJECTIVE: # find minimum val associated with each key in kv print method 1: brute force t=time.clock() d = dict() for k,v in kv: if k in d: if d[k] v: d[k] = v else: d[k] = v print time.clock()-t print d print print method 2: groupby t=time.clock() d = dict() kv_sorted = sorted(kv, key=lambda x: id(x[0])) for k, g in groupby( kv_sorted, key=lambda x: x[0] ): d[k] = min(gi[1] for gi in g) print time.clock()-t print d print print method 3: defaultdict t=time.clock() d = defaultdict(list) for k,v in kv: d[k].append(v) for k in d: d[k] = min(d[k]) print time.clock()-t print d -- http://mail.python.org/mailman/listinfo/python-list
Re: find minimum associated values
Paul Rubin wrote: How about something like: kv_sorted = sorted(kv, key=lambda x: (id(x[0]), x[1])) You mean like this? #sort by id and then value kv_sorted = sorted(kv, key=lambda x: (id(x[0]),x[1])) #groupby: first element in each group is object and its min value d =dict( g.next() for k,g in groupby( kv_sorted, key=lambda x: x[0] ) ) Yes, that appears to be fastest and is pretty easy to read. Thanks, Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: pairs from a list
I suppose my question should have been, is there an obviously faster way? Anyway, of the four ways below, the first is substantially fastest. Is there an obvious reason why? Thanks, Alan Isaac PS My understanding is that the behavior of the last is implementation dependent and not guaranteed. def pairs1(x): for x12 in izip(islice(x,0,None,2),islice(x,1,None,2)): yield x12 def pairs2(x): xiter = iter(x) while True: yield xiter.next(), xiter.next() def pairs3(x): for i in range( len(x)//2 ): yield x[2*i], x[2*i+1], def pairs4(x): xiter = iter(x) for x12 in izip(xiter,xiter): yield x12 -- http://mail.python.org/mailman/listinfo/python-list
Re: pairs from a list
Arnaud Delobelle wrote: According to the docs [1], izip is defined to be equivalent to: def izip(*iterables): iterables = map(iter, iterables) while iterables: result = [it.next() for it in iterables] yield tuple(result) This guarantees that it.next() will be performed from left to right, so there is no risk that e.g. pairs4([1, 2, 3, 4]) returns [(2, 1), (4, 3)]. Is there anything else that I am overlooking? [1] http://docs.python.org/lib/itertools-functions.html URL:http://bugs.python.org/issue1121416 fwiw, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: pairs from a list
Arnaud Delobelle wrote: pairs4 wins. Oops. I see a smaller difference, but yes, pairs4 wins. Alan Isaac import time from itertools import islice, izip x = range(51) def pairs1(x): return izip(islice(x,0,None,2),islice(x,1,None,2)) def pairs2(x): xiter = iter(x) while True: yield xiter.next(), xiter.next() def pairs3(x): for i in range( len(x)//2 ): yield x[2*i], x[2*i+1], def pairs4(x): xiter = iter(x) return izip(xiter,xiter) t = time.clock() for x1, x2 in pairs1(x): pass t1 = time.clock() - t t = time.clock() for x1, x2 in pairs2(x): pass t2 = time.clock() - t t = time.clock() for x1, x2 in pairs3(x): pass t3 = time.clock() - t t = time.clock() for x1, x2 in pairs4(x): pass t4 = time.clock() - t print t1, t2, t3, t4 Output: 0.317524154606 1.13436847421 1.07100930426 0.262926712753 -- http://mail.python.org/mailman/listinfo/python-list
pairs from a list
I want to generate sequential pairs from a list. Here is a way:: from itertools import izip, islice for x12 in izip(islice(x,0,None,2),islice(x,1,None,2)): print x12 (Of course the print statement is just illustrative.) What is the fastest way? (Ignore the import time.) Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
simple try/except question
Is the behavior below expected? If so, why is the exception not caught? Thanks, Alan Isaac x,y='','' try: x/y ... except TypeError: print 'oops' ... Traceback (most recent call last): File stdin, line 1, in module TypeError: unsupported operand type(s) for /: 'str' and 'str' -- http://mail.python.org/mailman/listinfo/python-list
Re: simple try/except question
Tim Chase wrote: It works for me(tm)... Python 2.4.3 Sorry to have left out that detail. Yes, it works for me in Python 2.4, but not in 2.5.1. The code I posted was copyied from the interpreter. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: simple try/except question
False alarm. Fresh start of interpreter and all is well. Apologies. Still tracking. Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: simple try/except question
Gabriel Genellina wrote: Perhaps you reassigned TypeError? Yes, that was it. Sheesh. Thanks! Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: Python and Combinatorics
none wrote: Is there some package to calculate combinatorical stuff like (n over k), i.e., n!/(k!(n - k!) ? Yes, in SciPy. Alan Isaac from scipy.misc.common import comb help(comb) Help on function comb in module scipy.misc.common: comb(N, k, exact=0) Combinations of N things taken k at a time. If exact==0, then floating point precision is used, otherwise exact long integer is computed. Notes: - Array arguments accepted only for exact=0 case. - If k N, N 0, or k 0, then a 0 is returned. -- http://mail.python.org/mailman/listinfo/python-list
unpickle from URL problem
I am on a Windows box.
I pickle a tuple of 2 simple objects with the pickle module.
It pickles fine. It unpickles fine.
I upload to a server.
I try to unpickle from the URL. No luck. Try it:
x1, x2 =
pickle.load(urllib.urlopen('http://www.american.edu/econ/notes/hw/example1'))
I change the filetype to unix. I upload again.
I try to unpickle from the URL. Now it works. Try it:
x1, x2 =
pickle.load(urllib.urlopen('http://www.american.edu/econ/notes/hw/example2'))
Why the difference?
Thank you,
Alan Isaac
--
http://mail.python.org/mailman/listinfo/python-list
Re: unpickle from URL problem
Marc 'BlackJack' Rintsch wrote: Pickles are *binary* files, not text files Actually not: http://docs.python.org/lib/node316.html These were created with protocol 0. But my question is about the different outcomes I observed. Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: unpickle from URL problem
Jean-Paul Calderone wrote: You shouldn't unpickle things you get from the network, since pickle can execute arbitrary code: http://jcalderone.livejournal.com/15864.html Yes, but I have my reasons. (This is not library code: I just want students to all be using the same objects for an exercise, and I need not to worry about their directory structure.) Can you explain the differences I see? Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: unpickle from URL problem
Hrvoje Niksic wrote: The first upload breaks the file. You uploaded it in (presumably FTP's) text mode, which changes \n - \r\n. But you download it using http, which specifies no such conversion in the opposite direction. No: I used binary upload both time. (Unless my ftp client is broken, and I think not.) The first example simply keeps the Windows eols, which are present in the pickled file on my Windows machine. This is the one created by pickle.dump. This file unpickles just fine. I altered the 2nd file before upload, changing to the Unix eol convention. This also unpickles just fine on my machine, but in addition the urllib download of this file unpickles just fine. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
announcement: OpenOpt and GenericOpt
OpenOpt and GenericOpt
==
Introducing two new optimization packages.
OpenOpt and GenericOpt are 100% Python
with a single dependency: NumPy.
For more detail see below and also
URL:https://projects.scipy.org/scipy/scikits/wiki/Optimization
OpenOpt
---
OpenOpt is new open source optimization framework.
OpenOpt is released under the BSD license.
The primary author and current maintainer of
OpenOpt is Dmitrey Kroshko email:openopt AT ukr.net
(Optimization Department, Cybernetics Institute, Ukrainian Science Academy)
OpenOpt goal: provide an open source alternative
to TomOpt TOMLAB (optimization framework for MATLAB)
and related optimization frameworks. Currently OpenOpt
offers connections to a variety of open source solvers,
primarily for unconstrained optimization. (See below.)
OpenOpt provides provides connections a vraity of solvers,
including those in GenericOpt, which are included.
(Users will need to download other solvers;
we provide URLs for the downloads.)
GenericOpt
--
GenericOpt is a toolkit for building specialized optimizers.
GenericOpt is released under the BSD license.
The primary author and current maintainer of GenericOpt is
Matthieu Brucher email:matthieu.brucher AT gmail.com
GenericOpt goal: provide an open source, extensible
toolit for component-wise construction of specialized
optimizers. GenericOpt allows users who want detailed control to construct
their own solvers by choosing among a variety of algorithm components
(currently, most choices are among step and line-search algorithms.)
Usage: see Matthieu Brucher's tutorial
URL:https://projects.scipy.org/scipy/scikits/wiki/Optimization/tutorial.
Limitation: currently GenericOpt provides only unconstrained solvers.
SciKits
---
The SciPy project is developing a collection of open source packages for
scientific computing which are allowed to have more dependencies and
more varied licenses than those allowed for SciPy proper.
In contrast to SciPy, the related scikits may host any
OSI-approved licensed code. See
URL:https://projects.scipy.org/scipy/scikits/
OpenOpt and GenericOpt are available together as a
SciPy scikit. The provides a unified optimization
framework along with a collection of solvers.
However, neither depends on the other.
OpenOpt Details
---
Key feature: a unified calling interface for all solvers,
a variety of pure Python solvers, and connections to
numerous external solvers.
Example::
from scikits.openopt import NLP
p = NLP(lambda x: (x-1)**2, 4)
r = p.solve('ralg')
In this example,
the objective function is (x-1)^2,
the start point is x0=4,
and 'ralg' specifies the name of solver involved.
See much more detailed example here
URL:http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/nlp_ALGENCAN.py
OpenOpt Connected External Solvers
--
Non-linear problems (NLP)
~
- ALGENCAN http://www.ime.usp.br/%7Eegbirgin/tango/py.php
(GPL)
- lincher (BSD) (all types of constraints and 1st derivatives),
- ralg (BSD) (currently unconstrained only)
- scipy_tnc and scipy_lbfgsb (box-bounded, requires scipy
installed, BSD)
Non-smooth problems (NSP)
~
- ralg (BSD)
- ShorEllipsoid (BSD)
(for small-scale problems with nVars = 1..10, former for
medium-scaled problems with nVars = 1...1000, requires r0)
Both are unconstrained for now.
Linear problems (LP)
- lp_solve http://sourceforge.net/projects/lpsolve (LGPL)
- glpk http://www.gnu.org/software/glpk/ (GPL)
- CVXOPT http://www.ee.ucla.edu/%7Evandenbe/cvxopt/ (GPL)
(currently glpk requires CVXOPT installed)
Mixed-integer problems (MILP)
~
- lp_solve http://sourceforge.net/projects/lpsolve
Quadratic problems (QP)
~~~
- CVXOPT http://www.ee.ucla.edu/%7Evandenbe/cvxopt/ (GPL)
(please note - NLP lincher solver requires QP solver, and
the only one for now is CVXOPT one)
Here you can look at examples for NLP
http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/nlp_1.py,
NSP
http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/nsp_1.py,
QP
http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/qp_1.py,
LP
http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/lp_1.py,
MILP
http://projects.scipy.org/scipy/scikits/browser/trunk/openopt/scikits/openopt/examples/milp_1.py
Acknowledgements
Development of OpenOpt was supported by Google through the
Google Summer of Code (GSoC) program, with Alan G. Isaac
as mentor. Additonal mentorship was provided by Jarrod Milman.
Debts to the SciPy community are many, but we would particularly
like to thank Nils Wagner.
Appeal
==
The primary author and current maintainer of OpenOpt is
Re: Any syntactic cleanup likely for Py3? And what about doc standards?
Torsten Bronger wrote: I like to use properties. However, Python already has properties. Their syntax is quite nice in my opinion, and rather explicit, too. Yes. Their only flaw is that they are not virtual (in C++ speak). In other words, you can't pass a self parameter to them. http://www.kylev.com/2004/10/13/fun-with-python-properties/ fwiw, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: create Powerpoint via com
Well, my needs were very limited so the result is too, but in case someone else just needs to get started: http://econpy.googlecode.com/svn/trunk/utilities/mso.py Comments, suggestions, additions welcom. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: create Powerpoint via com
How about chart creation (in Ppt 2003)? I do not see how to do this with Python. [EMAIL PROTECTED] wrote: You probably need to browse the COM object using PythonWin, which is a part of the ActiveState distro. You can also use Python's builtin function, dir, to find out various methods of COM. Here's some info in messing with charts in Excel, which should be similar to chart manipulation in PowerPoint. http://mail.python.org/pipermail/python-win32/2005-June/003511.html http://mail.python.org/pipermail/python-win32/2003-March/000839.html http://www.thescripts.com/forum/thread21565.html http://mathieu.fenniak.net/plotting-in-excel-through-pythoncom/ Thanks! Alan -- http://mail.python.org/mailman/listinfo/python-list
create Powerpoint via com
Can someone point me to a simple example or better yet tutorial for creating a Powerpoint using Python. Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: create Powerpoint via com
[EMAIL PROTECTED] wrote: Hope that helps! Yes indeed. Thanks! Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: create Powerpoint via com
[EMAIL PROTECTED] wrote: code OK, creating bulleted lists, or tables, or adding pictures is all straightforward. How about chart creation (in Ppt 2003)? I do not see how to do this with Python. Thanks, Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: Fastest way to convert a byte of integer into a list
On Jul 13, 9:54 am, Matimus [EMAIL PROTECTED] wrote: num = 255 numlist = [num i 1 for i in range(8)] Godzilla wrote: Thanks matimus! I will look into it... Watch out for the order, which might or might not match your intent. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: bool behavior in Python 3000?
Alan Isaac skrev: http://www.python.org/dev/peps/pep-0285/ Nis Jørgensen wrote: You forgot to quote this bit: [4)] Actually not. That is a different point. Ben seems bothered by this, but not me. I do not mind that True+1 is 2. I won't do it, but I do not object to it being possible. I do not like that True+True is 2. I do not like that bool(False-True) is True. I do not like that True and False are assignable, which clearly begs for bugs to pass unseen. True, False = False, True print True, False False True Who can like that I also generally agree with Steve, whose points keep being twisted beyond recognition. Also, tah is right about my underlying interest in arrays of bools (and more specifically, boolean matrices). I think Python 3000 is the right time to reconsider the ideal world that Guido mentions in PEP 285. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: bool behavior in Python 3000?
Stargaming wrote: I think Bjoern just wanted to point out that all those binary boolean operators already work *perfectly*. bool(False-True) True But reread Steven. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: bool behavior in Python 3000?
Bjoern Schliessmann wrote: Is there any type named bool in standard Python? type(True) type 'bool' Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: bool behavior in Python 3000?
Miles wrote: What boolean operation does '-' represent? Complementation. And as usual, a-b is to be interpreted as a+(-b). In which case the desired behavior is False-True = False+(-True)=False+False = False In response to Stargaming, Steve is making a point about the incoherence of certain arguments, not proposing an implementation. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: bool behavior in Python 3000?
Since it is seemingly ignored in most of the comments on this thread, I just want to remind that PEP 285 http://www.python.org/dev/peps/pep-0285/ says this: In an ideal world, bool might be better implemented as a separate integer type that knows how to perform mixed-mode arithmetic. I mentioned Python 3000 since that is an opportunity for an ideal world. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
bool behavior in Python 3000?
Is there any discussion of having real booleans in Python 3000? Say something along the line of the numpy implementation for arrays of type 'bool'? Hoping the bool type will be fixed will be fixed, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: allow scripts to use .pth files?
John Machin wrote: I got the impression that the OP was suggesting that the interpreter look in the directory in which it found the script. Right. I got the impression that the problem was that the package was not only not on sys.path but also not in the same directory as the script that wanted to import it. Right. I'm curious whether you think that the OP's use of .pth was a typo, and whether you have read this: http://docs.python.org/lib/module-site.html You seem to understand what I'm getting at. Thanks John. Alan Isaac (the OP above) -- http://mail.python.org/mailman/listinfo/python-list
Re: disappearing documentation of `coerce`
On 2007-07-05, Alan Isaac [EMAIL PROTECTED] wrote: Once upon a time, `coerce` was documented with the other built-ins. Neil Cerutti wrote: It's now documented in Library Reference 2.2 Non-essential Built-in Functions. Apparently it is no longer needed or useful, but only kept for backward compatibility. Thanks. I now see that it is going away: http://www.python.org/dev/peps/pep-3100/ Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: allow scripts to use .pth files?
On Jul 3, 7:35 am, Alan Isaac [EMAIL PROTECTED] wrote: Suppose I have a directory `scripts`. I'd like the scripts to have access to a package that is not installed, i.e., it is not on sys.path. On this list, various people have described a variety of tricks they use, but nobody has proposed a pretty way to allow this. I am therefore assuming there is not one. (?) How about allowing a `scripts.pth` file in such a `scripts` directory, to work like a path configuration file? (But to be used only when __name__==__main__.) Drawbacks? [EMAIL PROTECTED] wrote: import sys sys.path.append(../scripts) import Module_from_scripts_dir That is not actually an answer to the question. In any case, path manipulation in scripts is often pronounced not pretty. (And would also have to be done in every script file.) Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
disappearing documentation of `coerce`
Once upon a time, `coerce` was documented with the other built-ins. http://pydoc.org/1.5.2/__builtin__.html Now it is not. http://docs.python.org/lib/built-in-funcs.html Reason? Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
allow scripts to use .pth files?
Suppose I have a directory `scripts`. I'd like the scripts to have access to a package that is not installed, i.e., it is not on sys.path. On this list, various people have described a variety of tricks they use, but nobody has proposed a pretty way to allow this. I am therefore assuming there is not one. (?) How about allowing a `scripts.pth` file in such a `scripts` directory, to work like a path configuration file? (But to be used only when __name__==__main__.) Drawbacks? Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: equality comparison by default (was Re: Too many 'self' in python.That's a big flaw in this language.)
A.T.Hofkamp wrote: Hmm, maybe numbers in sets are broken then? a = 12345 b = 12345 a == b True a is b False set([a,b]) set([12345]) Numbers and my Car2 objects behave the same w.r.t. '==' and 'is', yet I get a set with 1 number, and a set with 2 cars. Something is wrong here imho. The point I intended to make was that having a default __hash__ method on objects give weird results that not everybody may be aware of. In addition, to get useful behavior of objects in sets one should override __hash__ anyway, so what is the point of having a default object.__hash__ ? The point is: let us have good default behavior. Generally, two equal numbers are two conceptual references to the same thing. (Say, the Platonic form of the number.) So it is good that the hash value is determined by the number. Similarly for strings. Two equal numbers or strings are **also** identical, in the sense of having the same conceptual reference. In contrast, two equal cars are generally not identical in this sense. Of course you can make them so if you wish, but it is odd. So *nothing* is wrong here, imo. Btw: a = 12 b = 12 a == b True a is b True Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: guidance needed: best practice for script packaging
My thanks to Gabriel and Josiah. Alan -- http://mail.python.org/mailman/listinfo/python-list
Re: equality comparison by default (was Re: Too many 'self' in python.That's a big flaw in this language.)
A.T.Hofkamp wrote: a = Car2(123) b = Car2(123) a == b True set([a,b]) set([Car2(123), Car2(123)]) I get a set with two equal cars, something that never happens with a set my math teacher once told me. Then your math teacher misspoke. You have two different cars in the set, just as expected. Use `is`. http://docs.python.org/ref/comparisons.html This is good behavior. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
guidance needed: best practice for script packaging
This is a simple question about actual practice. I just want to know how you (yes you) are approaching this problem. The problem: What is the recommended packaging of demo scripts or test scripts for a package to be distributed to others to play with. (I.e., without installing.) Example: Suppose I have the package structure: package/ __init__.py subpackage1/ __init__.py moduleXX.py subpackage2/ __init__.py moduleYY.py Important detail: moduleXX uses a relative import to access moduleYY. The goal: I have a script test.py that I want to distribute with the package. This script will import moduleXX to illustrate or test the module's use. Is it the case that this script cannot reasonably be bundled with `package`? (I.e., within its directory structure.) Note: If I put it in the `subpackage1` directory and just import moduleXX, I will get ValueError: Attempted relative import in non-package Note: If I put it in the `package` directory and import subpackage1.moduleXX, I will get ValueError: Attempted relative import beyond toplevel package Here is one hack, based on a suggestion of Alex Martelli http://mail.python.org/pipermail/python-list/2007-May/438250.html and others. - add a `scripts` subdirectory to `package` - use path manipulation to find the directory holding `package` - insert this directory in sys.path This hack works. However it has also been claimed that this approach is an insane for any shared code. Is it? If so, what is best practice? Note: I do not want to assume the package will be installed: a user should be able to play with it without installing it. This is a repeat question. The usual rule is, if you do not get an answer, you are asking the question in an unhelpful way. If my question is still unclear, I would appreciate any leads on how to clarify it. Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
relative import question: packaging scripts
What is the recommended packaging of demo scripts or test scripts for a package that has modules that use relative imports? Example: Suppose I have the package structure: package/ __init__.py subpackage1/ __init__.py moduleY.py subpackage2/ __init__.py moduleZ.py Important detail: moduleZ uses a relative import to access moduleY. The problem: I have a script test.py that I want to distribute with the package. It will import moduleZ to illustrate or test the module's use. Is it the case that this script cannot reasonably be bundled with `package`? (I.e., within its directory structure.) I cannot put it in the `subpackage2` directory and just import moduleZ, because then I will get ValueError: Attempted relative import in non-package I cannot put it in the `package` directory and import subpackage2.moduleZ, because then I will get ValueError: Attempted relative import beyond toplevel package The script could use path manipulation to find `package`, as suggested by Alex Martelli http://mail.python.org/pipermail/python-list/2007-May/438250.html and others. However it has also been claimed that this approach is an insane for any shared code. Is it? I do not want to assume the package will be installed: a user should be able to play with it without installing it. In this case, does the only sane thing to become to require any user to take the step of inserting the package location into sys.path and have test.py rely on the user having done this? Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Python plain-text database or library that supports joins?
Not Python, but maybe relevant: http://www.scriptaworks.com/cgi-bin/wiki.sh/NoSQL/HomePage Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
cannot have test scripts in packages?
This is really a repackaging of an earlier question, probably illustrating that I still do not understand relative imports. Suppose I have the package structure (taken from the example at http://www.python.org/dev/peps/pep-0328/) package/ __init__.py subpackage1/ __init__.py moduleY.py subpackage2/ __init__.py moduleZ.py Important detail: moduleZ uses a relative import to access moduleY. The problem: I have a script test.py that I want to distribute with the package. It will import moduleZ to illustrate or test the module's use. Is it the case that this script cannot reasonably be bundled with `package`? (I.e., within its directory structure.) I cannot put it in the `subpackage2` directory and just import moduleZ, because then I will get ValueError: Attempted relative import in non-package I cannot put it in the `package` directory and import subpackage2.moduleZ, because then I will get ValueError: Attempted relative import beyond toplevel package The script could then use path manipulation to find `package`, as suggested by Alex Martelli http://mail.python.org/pipermail/python-list/2007-May/438250.html and others. However it has also been claimed that this approach is an insane for any shared code. Btw, I do not want to assume the package will be installed: a user should be able to play with it without installing it. So if the package is not installed, is the only sane thing to do is require any user to take the step of inserting the package location into sys.path and have test.py rely on the user having done this? What is the recommended handling of demo or test scripts for a package? Thank you, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: File processing - is Python suitable?
ferrad wrote: I have large text files containing text, numbers, and junk. I want to delete large chunks process other bits, etc, much like I'd do in an editor, but want to do it automatically. Question: can I translate these types of rules into programmatical constructs that Python can use to process these files? Someone can. ;-) However if the file is structured, awk may be faster, since this sounds like the kind of report generation it was designed for. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: docs patch: dicts and sets
Raymond Hettinger [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Another way to put it is that the docs are sufficient when they say that set ordering is arbitrary. That should be a cue to not have *any* expectations about the internal ordering of sets and dicts. You are usually more careful. 1. Please do not conflate two issues here. It confuses people like Richard T. Did *anyone* who participated in the initial conversation express an expectation that set ordering is not arbitrary? No. Not one. What surprised people was that this ordering could vary between two *sequential* executions of an *unchanged* source. Martin dismisses this by simply asserting (on what basis?) that anyone who was surprised lacks Python experience, and that to address this in any way would make the reference library assume the role of a tutorial. Not very plausible, IMO, given the rest of the library documentation. 2. You say it the existing docs should be a cue, and yet they clearly did not provide enough guidance to an ordinary user (me) and some more sophisticated users. So the docs should be a cue to people who do not need a cue. Do I understand you correctly? 3. Finally, please do not claim that the docs say that set ordering is arbitrary. At least not the docs we have benn talking about: http://docs.python.org/lib/types-set.html It is fascinating that you would confuse this, since it is the core of the proposed documentation patch (although the proposed language was indeterminate rather than arbitrary). So it also seems you are now claiming that the patch should not be in because of the presence of language that is in fact not there. Look, I was just trying to help other users who might be as surprised as I was. As I said, I am not attached to any language, and in fact I just used the proposals of others. I just wanted there to be some clue for users who read the docs. If you prefer to leave such users baffled, so be it. My effort is exhausted. Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: docs patch: dicts and sets
I submitted the language based on Bill and Carsten's proposals: https://sourceforge.net/tracker/?func=detailatid=105470aid=1721372group_id=5470 That language has been rejected. You many want to read the discussion and see if acceptible language still seems discoverable. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
docs patch: dicts and sets
This discussion ended abruptly, and I'd like to see it reach a conclusion. I will attempt to synthesize Bill and Carsten's proposals. There are two proposed patches. The first is to http://docs.python.org/lib/typesmapping.html where it is proposed for footnote (3) to state: Keys and values are listed in an arbitrary order. This order is indeterminate and generally depends on factors outside the scope of the containing program. However, if items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are called with no intervening modifications to the dictionary, the lists will directly correspond. The second is for http://docs.python.org/lib/types-set.html where the proposal is to append a new sentence to the 2nd paragraph: Iteration over a set returns elements in an indeterminate order,which generally depends on factors outside the scope of the containing program. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: change of random state when pyc created??
This is an attempt to synthesize Bill and Carsten's proposals. http://docs.python.org/lib/typesmapping.html: for footnote (3) Keys and values are listed in an arbitrary order. This order is indeterminate and generally depends on factors outside the scope of the containing program. However, if items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are called with no intervening modifications to the dictionary, the lists will directly correspond. http://docs.python.org/lib/types-set.html: append a new sentence to 2nd par. Iteration over a set returns elements in an indeterminate order, which generally depends on factors outside the scope of the containing program. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
docs patch: dicts and sets
This is an attempt to synthesize Bill and Carsten's proposals. (I'm changing the subject line to better match the topic.) http://docs.python.org/lib/typesmapping.html: for footnote (3) Keys and values are listed in an arbitrary order. This order is indeterminate and generally depends on factors outside the scope of the containing program. However, if items(), keys(), values(), iteritems(), iterkeys(), and itervalues() are called with no intervening modifications to the dictionary, the lists will directly correspond. http://docs.python.org/lib/types-set.html: append a new sentence to 2nd par. Iteration over a set returns elements in an indeterminate order,which generally depends on factors outside the scope of the containing program. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: change of random state when pyc created??
Carsten Haese [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] I was simply pointing out all the ways in which you made it difficult for the community to explain your problem. And without that community, I would still not have a clue. Thanks to all! Please feel free to suggest specific wording changes to make the documentation more useful. I'm sure my first pass will be flawed, but here goes: http://docs.python.org/lib/typesmapping.html: to footnote (3), add phrase which may depend on the memory location of the keys to get: Keys and values are listed in an arbitrary order, which may depend on the memory location of the keys. This order is non-random, varies across Python implementations, and depends on the dictionary's history of insertions and deletions. http://docs.python.org/lib/types-set.html: append a new sentence to 2nd paragraph Iteration over a set returns elements in an arbitrary order, which may depend on the memory location of the elements. fwiw, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: change of random state when pyc created??
Alan Isaac requested: http://docs.python.org/lib/typesmapping.html: to footnote (3), add phrase http://docs.python.org/lib/types-set.html: append a new sentence to 2nd paragraph Hamilton, William [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Keys and values are listed in an arbitrary order. This order is non-random, varies across Python implementations, and depends on the dictionary's history of insertions and deletions as well as factors outside the scope of the containing program. Iteration over a set returns elements in an arbitrary order, which may depend on factors outside the scope of the containing program. I think this is good and might have clued me in. At least I'd have had a fighting chance this way. Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: change of random state when pyc created??
Peter Otten [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Alan Isaac wrote: There is nothing wrong with the random module -- you get the same numbers on every run. When there is no pyc-file Python uses some RAM to create it and therefore your GridPlayer instances are located in different memory locations and get different hash values. This in turn affects the order in which they occur when you iterate over the GridPlayer.players_played set. Thanks!! This also explains Steven's results. If I sort the set before iterating over it, the anomaly disappears. This means that currently the use of sets (and, I assume, dictionaries) as iterators compromises replicability. Is that a fair statement? For me (and apparently for a few others) this was a very subtle problem. Is there a warning anywhere in the docs? Should there be? Thanks again!! Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: change of random state when pyc created??
Robert Kern wrote: http://docs.python.org/lib/typesmapping.html Keys and values are listed in an arbitrary order which is non-random, varies across Python implementations, and depends on the dictionary's history of insertions and deletions. Alan G Isaac wrote: Even this does not tell me that if I use a specified implementation that my results can vary from run to run. That is, it still does not communicate that rerunning an *unchanged* program with an *unchanged* implementation can produce a change in results. Robert Kern [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] The last clause does tell me that. 1. About your reading of the current language: I believe you, of course, but can you tell me **how** it tells you that? To be concrete, let us suppose parallel language were added to the description of sets. What about that language should allow me to anticipate Peter's example (in this thread)? 2. About possibly changing the docs: You are much more sophisticated than ordinary users. Did this thread not demonstrate that even sophisticated users do not see into this implication immediately? Replicability of results is a huge deal in some circles. I think the docs for sets and dicts should include a red flag: do not use these as iterators if you want replicable results. (Side note to Carsten: this does not require listing every little thing.) Cheers, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
