Overlooked Python Built-Ins

Page Trail: [[ Overlooked Python Built-Ins ]]
2009-05-22 23:52
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So, I just realized that I re-implemented two built-in Python functions on a small project I'm working on for ETSZONE. I just didn't know that these existed, so I'm writing about them here in case you've overlooked them too.


This is useful if you want to sort a copy of a list. Use sorted() instead of copying the list and then using list.sort().

This was my re-implementation (and I think I still like its name better):

def sort(seq, **args):
    x = list(seq)
    return x

The sorted function has been available since Python v2.4.


This is useful when you want a foreach loop, but you also need a loop counter around. Use enumerate() instead of keeping a counter elsewhere.

For example, I was writing out a spreadsheet with ooolib-python. For each spreadsheet cell to write, I had to specify row and column indexes. I could write more natural loops with enumerate, while still having a counter to use as a row or column index.

This was my re-implementation (and its name would have never caught on):

def indexiter(iterable):
    return zip(range(len(iterable)), iterable)

The enumerate function has been available since Python v2.3. Read about the optional start parameter in the docs - it looks useful, but it's new in Python 2.6.

This shows that it's a good idea to occasionally browse back through the very basic support a language gives you, since you might just find a couple useful tools in there that you had overlooked. If you're into Python, start here.