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

Here's a pretty easy way:

sum(zip(l, l), tuple())

It duplicates each item, and adds them to a tuple. If you don't want a tuple (as I suspect), you can call list on the the tuple:

list(sum(zip(l, l), tuple()))

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A few other versions (that yield lists):

list(sum(zip(l, l), ()))

sum([list(i) for i in zip(l, l)], [])

sum(map(list, zip(l, l)), [])