CODEWITHSUNDEEP
pythonlistsortingpython-3.xnested
user3930051
user3930051

Reputation:

Nested list sort python 3

I am a python beginner--headbangin'. This is a very basic question and I can't seem to find any straight forward answer, either using google or StackOverFlow.

QUESTION: I have a nested list:

 l = [
 [1,4,3,n]
 [2,2,4,n]
 [3,1,5,n]
 ]

I want to sort the entire list by the second value smallest to largest. I will end up sorting the list again by the third value... and nth value of each nested list.

HOW WOULD ONE SORT based on the SECOND, THIRD, Nth value?

A key is mentioned, but "key=lambda" is often used and that just confuses me more.

EDIT: Thank you guys for your help. I was able to use your advice to solve the problem at hand. I would upvote you but apparently, I can't yet show my thanks in that form. I will return someday and give you your reputation bumps.

Upvotes: 5

Views: 5699

Answers (2)

Adem Öztaş
Adem Öztaş

Reputation: 21446

You can try like this,

>>> l = [[1,4,3], [2,2,4], [3,1,5]]
>>> sorted(l, key=lambda x: x[1])
[[3, 1, 5], [2, 2, 4], [1, 4, 3]]

or:

>>> l.sort(key=lambda x: x[1])
>>> l
[[3, 1, 5], [2, 2, 4], [1, 4, 3]]

Upvotes: 5

idjaw
idjaw

Reputation: 26578

Can also be done using operator

Inside operator.itemgetter(1) you are indicating which index you want to sort on. So, in in this case we are specifying 1 which is the second item. 

import operator

l = [[1,4,3], [2,2,4], [3,1,5]]
print(sorted(l, key=operator.itemgetter(1)))

output:

[[3, 1, 5], [2, 2, 4], [1, 4, 3]]

Upvotes: 6

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