Python: How to extend or append multiple elements in list comprehension format?

Question

I\'d like to get a nice neat list comprehension for this code or something similar!

extra_indices = []
for i in range(len(indices)):
    index = indices[i]
          


        

Answer 1

code below should do the equivalant of your code, assuming indices is a list of integer

from itertools import chain
extra_indices = list(chain(*([x,x+1,x+2] for x in indices)))

>>> indices = range(3)
>>> list(chain(*([x,x+1,x+2] for x in indices)))
>>> [0, 1, 2, 1, 2, 3, 2, 3, 4]

Answer 2

You can use two loops in list comp -

extra_indices = [index+i for index in indices for i in range(3)]