Repeat each item in a list a number of times specified in another list

Question

I have two lists, x and y:

>>> x = [2, 3, 4]
>>> y = [1, 2, 3]

I want to use these to create a

Answer 1

One way to achieve this is via using .elements() function of collections.Counter() along with zip. For example:

>>> from collections import Counter

>>> x = [2, 3, 4]
>>> y = [1, 2, 3]

# `.elements()` returns an object of `itertool.chain` type, which is an iterator.
# in order to display it's content, here type-casting it to `list` 
>>> list(Counter(dict(zip(x,y))).elements())
[2, 3, 3, 4, 4, 4]