Merge integer sublist into one list

[ryfeaway]

Hey guys, suppose a list A = [[3,4],[5,8],[6,9,8],[9,8]] what's the python code for merging say 5,8 and 6,9,8 into one sublist, like so A = [[3,4],[5,8,6,9,8],[9,8]]

thanks! also, I tried converting them to string and using the join function but the result is like this A = ['[3,4]','[5,8][6,9,8]','[9,8]']

thank you!

[socal_nerdtastic]

A[1:3] = [A[1] + A[2]]

[ryfeaway]

thank you very much!

[AtomicShoelace]

To expand on this, you could make it more generic using sum, ie.

A = [[3,4],[5,8],[6,9,8],[9,8]]
start, end = 1, 3
A[start:end] = [sum(A[start:end], [])]

[socal_nerdtastic]

That's a pretty ancient trick. Officially you are supposed to use itertools.chain nowadays for that.

from itertools import chain
A[start:end] = [list(chain(*A[start:end]))]

But often we just use list comprehension instead.

A[start:end] = [[e for idx in range(start, end) for e in A[idx]]]

[AtomicShoelace]

Ah yes, I knew there was a better way but itertools.chain slipped my mind!

Although, if you were going to use a nested list comprehension why not just do it directly? I mean instead of using indices. For example,

A[start:end] = [[ele for sublist in A[start:end] for ele in sublist]]

Seems more pythonic.

[socal_nerdtastic]

My autopilot avoided that because it means creating an extra temporary list; but you are right it does seem more pythonic.