renumerate

Reverse enumerate

renumerate

Reverse enumerate.

Overview

renumerate (sequence, start=len(sequence)-1, end=0):

Return an enumerate object.

sequence must be an object that has a __reversed__() method or supports the

sequence protocol (the __len__() method and the __getitem__() method with

integer arguments starting at 0).

The __next__() method of the iterator returned by renumerate() returns a tuple

containing a count (from start which defaults to len(sequence) - 1 or ends at

end which defaults to 0 - but not both) and the values obtained from reverse

iterating over sequence.

>>> from renumerate import renumerate
>>> seasons = ['Spring', 'Summer', 'Fall', 'Winter']
>>> list(renumerate(seasons))
[(3, 'Winter'), (2, 'Fall'), (1, 'Summer'), (0, 'Spring')]
>>> list(renumerate(seasons, start=4))
[(4, 'Winter'), (3, 'Fall'), (2, 'Summer'), (1, 'Spring')]
>>> list(renumerate(seasons, end=2))
[(5, 'Winter'), (4, 'Fall'), (3, 'Summer'), (2, 'Spring')]

Equivalent to:

def renumerate(sequence, start=None, end=None):
    if start is not None and end is not None:
        raise TypeError("renumerate() only accepts start argument or end argument"
                        " - not both.")
    if start is None: start = len(sequence) - 1
    if end   is None: end   = 0
    n = start + end
    for elem in sequence:
        yield n, elem
        n -= 1