`recipes`

Functions

`countby`(key, seq)	Count elements of a collection by a key function
`partitionby`(func, seq)	Partition a sequence according to a function

countby(key, seq)

Count elements of a collection by a key function

>>> countby(len, ['cat', 'mouse', 'dog'])
{3: 2, 5: 1}

>>> def iseven(x): return x % 2 == 0
>>> countby(iseven, [1, 2, 3])  
{True: 1, False: 2}

See also

groupby

partitionby(func, seq)

Partition a sequence according to a function

Partition s into a sequence of lists such that, when traversing s, every time the output of func changes a new list is started and that and subsequent items are collected into that list.

>>> is_space = lambda c: c == " "
>>> list(partitionby(is_space, "I have space"))
[('I',), (' ',), ('h', 'a', 'v', 'e'), (' ',), ('s', 'p', 'a', 'c', 'e')]

>>> is_large = lambda x: x > 10
>>> list(partitionby(is_large, [1, 2, 1, 99, 88, 33, 99, -1, 5]))
[(1, 2, 1), (99, 88, 33, 99), (-1, 5)]

recipes

Functions

`recipes`