CODEWITHSUNDEEP
python
jamborta
jamborta

Reputation: 5210

insert multiple elements to list at position

Is there a way to insert multiple elements to a list during a list comprehension in python?

For example:

def a():
   return [6,7,8]
[a() if i==2 else i for i in range(4)]
[0, 1, [6, 7, 8], 3]

Would it be possible to get a flat list in one go (function a could return the data in any format).

thanks,

Upvotes: 1

Views: 468

Answers (2)

shuttle87
shuttle87

Reputation: 15934

This seems a bit nasty but will work with various datatypes:

import itertools
def a():
   return [6,7,8]
l = list(itertools.chain.from_iterable([a() if i==2 else [i] for i in range(4)]))
print(l)

>>>[0, 1, 6, 7, 8, 3]

We can see this also works with other return types from a:

def a():
   return {6,7,8}

>>>[0, 1, 8, 6, 7, 3]

This is already complex enough where I would question going with a one liner approach. It's probably more readable to break this down more.

Upvotes: 1

Jeff Mandell
Jeff Mandell

Reputation: 863

def a(): return [6,7,8]
l = [a() if i==2 else [i] for i in range(4)]
flat = [item for sublist in l for item in sublist]

You could also do it in one go if you combine the last two lines, but that wouldn't be very pythonic.

Upvotes: 1

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