Duplicate elements in a list

Question

I have a list in Python:

l = [\'a\', \'c\', \'e\', \'b\']

I want to duplicate each element immediately next to the original.

Answer 1

import itertools

ll = list(itertools.chain.from_iterable((e, e) for e in l))

At work:

>>> import itertools
>>> l = ['a', 'c', 'e', 'b']
>>> ll = list(itertools.chain.from_iterable((e, e) for e in l))
>>> ll
['a', 'a', 'c', 'c', 'e', 'e', 'b', 'b']

As Lattyware pointed out, in case you want more than just double the element:

from itertools import chain, repeat

ll = list(chain.from_iterable(repeat(e, 2) for e in l))