libb.grouper

grouper(iterable, n, incomplete='fill', fillvalue=None)[source]

Group elements from iterable into fixed-length groups of length n.

>>> list(grouper('ABCDEF', 3))
[('A', 'B', 'C'), ('D', 'E', 'F')]

The keyword arguments incomplete and fillvalue control what happens for iterables whose length is not a multiple of n.

When incomplete is ‘fill’, the last group will contain instances of fillvalue.

>>> list(grouper('ABCDEFG', 3, incomplete='fill', fillvalue='x'))
[('A', 'B', 'C'), ('D', 'E', 'F'), ('G', 'x', 'x')]

When incomplete is ‘ignore’, the last group will not be emitted.

>>> list(grouper('ABCDEFG', 3, incomplete='ignore', fillvalue='x'))
[('A', 'B', 'C'), ('D', 'E', 'F')]

When incomplete is ‘strict’, a subclass of ValueError will be raised.

>>> iterator = grouper('ABCDEFG', 3, incomplete='strict')
>>> list(iterator)  
Traceback (most recent call last):
...
UnequalIterablesError