itertools.groupby

Describing itertools.groupby(iterable)

  • The groupby function is used to:

    • Cycle through each element of an iterable
    • Grouping similar and consecutive elements into keys
  • This iterable is based on the itr parameter
  • groupby returns an iterator that is made up of tuples
  • These tuples are represented as a key and group pair
  • Each tuple belongs to a distinct group
  • The key refers to an individual element
  • The group refers to the grouping of similar, consecutive elements associated with the key

Illustrating the groupby Function

>>> from itertools import groupby
>>> letters = 'mississippi'

>>> [i for i in groupby(letters)]
[('m', <itertools._grouper at 0x109b77978>),
 ('i', <itertools._grouper at 0x109b77f60>),
 ('s', <itertools._grouper at 0x109b77e10>),
 ('i', <itertools._grouper at 0x109b77908>),
 ('s', <itertools._grouper at 0x109b77710>),
 ('i', <itertools._grouper at 0x109b77198>),
 ('p', <itertools._grouper at 0x109b77a90>),
 ('i', <itertools._grouper at 0x109b77ba8>)]

>>> [k for k, g in groupby(letters)]
['m', 'i', 's', 'i', 's', 'i', 'p', 'i']

>>> [g for k, g in groupby(letters)]
[<itertools._grouper at 0x109cadc88>,
 <itertools._grouper at 0x109cad630>,
 <itertools._grouper at 0x109cad9e8>,
 <itertools._grouper at 0x109cad4a8>,
 <itertools._grouper at 0x109cad4e0>,
 <itertools._grouper at 0x109cad6a0>,
 <itertools._grouper at 0x109cad7b8>,
 <itertools._grouper at 0x109cada20>]

>>> [list(g) for k, g in groupby(letters)]
[['m'], ['i'], 
 ['s', 's'], ['i'], 
 ['s', 's'], ['i'],
 ['p', 'p'], ['i']]

References

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