Another exhilarating feature which I like is compress which filters elements from data returning only those that have a corresponding element in selectors that evaluates to True. I use this frequently as a Data Scientist.
Been partial to toolz (esp the cytoolz implementation) myself.
[Comment removed by moderator pushcx: Removing sockpuppet.]
Yeah the itertools module is really awesome. One of the best feature is it can be used along with the various methods of operators module as well.