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How to handle exceptions in a list comprehensions?

I have some a list comprehension in Python in which each iteration can throw an exception. For instance, if I have: I’ll get a ZeroDivisionError exception in the 3rd element. How can I handle this exception and continue execution of the list comprehension? The only way I can think of is to use a helper function: But this looks a

match an alternative url – regular expression django urls

I want a Django URL with just 2 alternatives /module/in/ or /module/out/ I’m using But it matches other patterns like /module/i/, /module/n/ and /module/ou/. Any hint is appreciated :) Answer Try r’^(?P<status>in|out)/$’ You need to remove w+, which matches one or more alphanumeric characters or underscores. The regular expression suggested in bstpierre’s answer, ‘^(?P<status>w+(in|out))/$’ will match helloin, good_byeout and so

Log output of multiprocessing.Process

Is there a way to log the stdout output from a given Process when using the multiprocessing.Process class in python? Answer The easiest way might be to just override sys.stdout. Slightly modifying an example from the multiprocessing manual: And running it: $ ls m.py $ python m.py $ ls 27493.out 27494.out m.py $ cat 27493.out function f module name: __main__

How can I implement decrease-key functionality in Python’s heapq?

I know it is possible to realize decrease-key functionality in O(log n) but I don’t know how? Answer To implement “decrease-key” effectively, you’d need to access the functionality “decrement this element AND swap this element with a child until heap condition is restore”. In heapq.py, that’s called _siftdown (and similarly _siftup for INcrementing). So the good news is that the

Format floats with standard json module

I am using the standard json module in python 2.6 to serialize a list of floats. However, I’m getting results like this: I want the floats to be formated with only two decimal digits. The output should look like this: I have tried defining my own JSON Encoder class: This works for a sole float object: But fails for nested

fcntl substitute on Windows

I received a Python project (which happens to be a Django project, if that matters,) that uses the fcntl module from the standard library, which seems to be available only on Linux. When I try to run it on my Windows machine, it stops with an ImportError, because this module does not exist here. Is there any way for me

Is there a function to determine which quarter of the year a date is in?

Sure I could write this myself, but before I go reinventing the wheel is there a function that already does this? Answer Given an instance x of datetime.date, (x.month-1)//3 will give you the quarter (0 for first quarter, 1 for second quarter, etc — add 1 if you need to count from 1 instead;-). Originally two answers, multiply upvoted and

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