Python: str.split() - is it possible to only specify the "limit" parameter?

Question

I want to split a string on whitespaces (default behavior), but I want it to split it only once - I.e. I want it to return an array with 2 items at most.

If it is not possible - i.e. if for specifying the limit I have to also specify the pattern - could you please tell how to specify the default one?

Answer 1

Split string on consecutive whitespace^† at most maxsplit times^††

^† Resulting list will contain no leading or trailing empty strings ("") if the string has leading or trailing whitespace
^†† Splits are made left to right. To split the other way (right to left), use the str.rsplit() method (requires Python 2.4+)

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Python 2

str.split(sep[, maxsplit]])

Use str.split(None, maxsplit)

Note:
Specifying sep as None ≝ not specifying sep

str.split(None, -1) ≝ str.split() ≝ str.split(None)

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Python 3

str.split(sep=None, maxsplit=-1)

Option A: Stick with positional arguments (Python 2 option): str.split(None, maxsplit)

>>> ' 4 2 0 '.split(None, 420)
['4', '2', '0']

Option B (personal preference, using keyword arguments): str.split(maxsplit=maxsplit)

>>> ' 4 2 0 '.split(maxsplit=420)` 
['4', '2', '0']

Answer 2

This works:

>>> 'a b c'.split(None, 1)
['a', 'b c']

The docstring:

S.split(sep=None, maxsplit=-1) -> list of strings

Return a list of the words in S, using sep as the delimiter string. If maxsplit is given, at most maxsplit splits are done. If sep is not specified or is None, any whitespace string is a separator and empty strings are removed from the result.

You should explore at the interactive prompt:

>>> help('a'.split)

In IPython just use a question mark:

In [1]:  s = 'a'
In [2]:  s.split?

I would suggest using IPython and especially the Notebook. This makes this kind of exploration much more convenient.