Python Tips

The “with” statement

This is just incredibly beautiful code.

Check out the source for more details on Python’s “with” statement if you’re interested.

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Too useful not to know.  Source is here.

max and min accept a sorting function

Instead of writing out this:

def best(candidates, scoref):
    '''Use scoref to find the candidate with the highest score.'''
    highest_score = float('-inf')
    best = None
    for candidate in candidates:
	candidate_score = scoref(candidate)
        if candidate_score > highest_score:
            highest_score = candidate_score
            best = candidate
    return best

You can just write:

max(iterable, key=scoref)

Don’t forget the “key” keyword, or Python will think you are comparing the list against the function. This is pretty cool because it makes things like getting the max value in a dictionary trivial.

>>> a = {'a': 1, 'b':2, 'c':3}
>>> a
{'a': 1, 'c': 3, 'b': 2}
>>> max(a, key=lambda x: a[x])
'c'

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