Python: duplicating each element in a list

Question

What's the most pythonic way to do the following? It can either modify the old list or create a new list.

oldList = [1, 2, 3, 4]

newList = [1, 1, 2, 2, 3, 3, 4, 4]

Answer 1

Using list comprehension:

>>> oldList = [1, 2, 3, 4]
>>> newList = [x for x in oldList for _ in range(2)]
>>> newList
[1, 1, 2, 2, 3, 3, 4, 4]

Above list comprehension is similar to following nested for loop.

newList = []
for x in oldList:
    for _ in range(2):
        newList.append(x)

Answer 2

If you're really into functional programming:

from itertools import chain,izip
newList = list(chain(*izip(oldList,oldList)))

@falsetru's answer is more readable, so that likely meets the "most pythonic" litmus test.