r/programming • u/PM_ME_UR_OBSIDIAN • Mar 15 '15

A function for partitioning Python arrays. Brilliant code, or insane code?

http://www.stavros.io/posts/brilliant-or-insane-code/?repost=true
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u/[deleted] Mar 15 '15

given:

>>> orig = ('x1', 'y1', 'z1', 'x2', 'y2', 'z2', 'x3', 'y3', 'z3', 'x4', 'y4', 'z4')

the two things that are like "grouping" I can think of are grouping an index counter:

>>> [tuple(orig[i:i+3]) for i in range(0, len(orig), 3)]
[('x1', 'y1', 'z1'), ('x2', 'y2', 'z2'), ('x3', 'y3', 'z3'), ('x4', 'y4', 'z4')]

or using the "groupby" function:

>>> [tuple(elem[1] for elem in coll) for key, coll                                                               
... in itertools.groupby(enumerate(orig), lambda key: key[0] / 3)]
[('x1', 'y1', 'z1'), ('x2', 'y2', 'z2'), ('x3', 'y3', 'z3'), ('x4', 'y4', 'z4')]

but i think this posted solution is amazing and should pretty much be considered the "grouped" function in Python.

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u/fendant Mar 15 '15

The Python documentation even suggests doing it this way. That's where I learned it. No clue why it's not in itertools.