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From: Peter Otten <__peter__@web.de>
Newsgroups: comp.lang.python
Subject: Re: repeat items in a list
Date: Wed, 30 Mar 2016 17:52:09 +0200
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Michael Selik wrote:

> I prefer itertools.chain.from_iterable to the sum trick.
> 
>>>> from itertools import chain
>>>> lst = list('abc')
>>>> list(chain.from_iterable([s]*3 for s in lst))
> ['a', 'a', 'a', 'b', 'b', 'b', 'c', 'c', 'c']

If you want to make this completely lazy:

>>> from functools import partial
>>> from itertools import repeat, chain
>>> items = list("abc")
>>> list(chain.from_iterable(map(partial(repeat, times=3), items)))
['a', 'a', 'a', 'b', 'b', 'b', 'c', 'c', 'c']