CODEWITHSUNDEEP
pythonlist
BlueDotRo
BlueDotRo

Reputation: 101

Add an element to each list in a list in python

I have a list like this:

a = [(1,2,3,4), (2,3,2,2), (33,221,22,1) ...]

and I want to add for each item in the list a 5th value, for example:

new_a = [(1,2,3,4,"new"), (2,3,2,2,"new"), (33,221,22,1,"new") ...]

How can I do that because a.list or a.add freeze my computer.

for item in a:
  a.add("new") or a.append("new")

Upvotes: 1

Views: 81

Answers (2)

Adem Öztaş
Adem Öztaş

Reputation: 21446

You can use map

>>> map(lambda x: x + ('new',), a)
[(1, 2, 3, 4, 'new'), (2, 3, 2, 2, 'new'), (33, 221, 22, 1, 'new')]

Upvotes: 0

Cristian Lupascu
Cristian Lupascu

Reputation: 40516

The inner items are not lists, they are tuples. Tuples are immutable. Therefore, you probably need to create new tuples that contain the values you want:

new_a = [x + ('new',) for x in a]

This code iterates through all tuples present in a and for each one creates a new tuple consisting of the values of the original, plus the value 'new' (the value ('new',) is a tuple literal: it creates a new tuple with one value).

In the end, all the values created are assigned to the new list.

Upvotes: 2

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