How to insert multiple values by index into list at one time

Question

I was wondering if there was a way to insert multiple variables into a list at one time using the same index. So for example, let's say we have a list of

[a, b, c]

and

[0,1,2,3,4]

and I wanted to insert the first list such that the end result is,

[a, 0, 1, b, 2, 3, c, 4]

But if I was going to do it individually using list.insert(pos, value)and used the positions of [0, 2, 4] then the subsequent positions used becomes invalid since it was relating to the old list of 5 elements instead of 6 now.

Any suggestions?

Answer 1

list_a = [0,1,2,3,4]
list_b = ["a", "b", "c"]
pos    = [0, 2, 4]

assert(len(list_b) == len(pos))
acc = 0
for i in range(len(list_b)):
    list_a.insert(pos[i]+acc, list_b[i])
    acc += 1

print(list_a)

['a', 0, 1, 'b', 2, 3, 'c', 4]

Answer 2

One simple option is to add the items starting with the position with highest value, and then continue with the 2nd highest value, etc.

This way you can using the original method, without any problem of "old/new position"

Answer 3

One ways without using a list comprehension:

>>> a = [0,1,2,3,4]
>>> b = ['a', 'b', 'c']
>>> ind = [0, 2, 4]
>>> d = dict(zip(ind, b))

>>> [t for k in [(d.get(i),j) for i,j in enumerate(a)] for t in k if t is not None]
['a', 0, 1, 'b', 2, 3, 'c', 4]