Can I extend list in Python with prepend elements instead of append?

You can assign to a slice:

a[:0] = b

Demo:

>>> a = [1,2,3]>>> b = [4,5,6]>>> a[:0] = b>>> a[4, 5, 6, 1, 2, 3]

Essentially, list.extend() is an assignment to the list[len(list):] slice.

You can 'insert' another list at any position, just address the empty slice at that location:

>>> a = [1,2,3]>>> b = [4,5,6]>>> a[1:1] = b>>> a[1, 4, 5, 6, 2, 3]

python list append prepend

This is what you need ;-)

a = b + a

python list append prepend

import collectionsa = collections.deque([1, 2, 3])b = [4, 5, 6]a.extendleft(b[::-1])

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