Sorting a 2D list in Python

Question

I have a 2D list:

mylist = [[9,7, 2, 2], [1,8, 2, 2], [2,9, 2, 2]]

Using a sort function, the list is sorted like this:

[[1, 8, 2, 2], [2, 9, 2, 2], [9, 7, 2, 2]]

But I want to sort this list like this:

[[9, 7, 2, 2],[1, 8, 2, 2], [2, 9, 2, 2]]

in which instead of the first digit of the list, I want to sort it by the last digit, like using a sort function - it sorted by the first digit of the list. I want to sort it by the last digit like 7 is smaller than 8 and 9 so 7 comes first.

list.sort(key=lambda x: x[::-1])?

Primusa
– Primusa

2018-07-07 04:57:32 +00:00
Commented Jul 7, 2018 at 4:57 — Primusa
– Primusa, Commented Jul 7, 2018 at 4:57

Nidhin Sajeev · Accepted Answer · 2018-07-07 05:10:16Z

5

use sorted() with lambda Try this

In [1]: a=[[9, 7, 2, 2],[1, 8, 2, 2], [2, 9, 2, 2]]
In [4]: sorted(a,key=lambda a:a[::-1])
Out[4]: [[9, 7, 2, 2], [1, 8, 2, 2], [2, 9, 2, 2]]

edited Jul 7, 2018 at 5:10

answered Jul 7, 2018 at 4:58

Nidhin Sajeev

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1 Comment

tarunsharma967 Over a year ago

In your answer you fixed it to second digit, i want to sort it by looking from end if last digits are same then it should look at second last digit.

Andrej Kesely · Accepted Answer · 2018-07-07 05:11:38Z

3

You can try:

sorted(a,key=lambda a:list(reversed(a)))

Output:

[[9, 7, 2, 2], [1, 8, 2, 2], [2, 9, 2, 2]]

answered Jul 7, 2018 at 5:11

Andrej Kesely

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