Python sorting arrays by element contained?

Question

I'm looking to take a list of lists and sort them by an element contained in the contained lists. For clarification, I want to have a list like this code

myList = []
myList.append([1, 2, 3])
myList.append([1, 1, 1])
myList.append([1, 3, 2])

and then sort the elements of list by the last element of each contained list and it would end up looking like this

           |
myList = ( v
    [1, 2, 3],
    [1, 3, 2],
    [1, 1, 1])

I also have the numpy library imported in this project. I was looking at argsort for numpy but I don't think you can sort it along an axis of an element

Don't use `list` as a variable name because it's built into python. — BallpointBen, Nov 15 '19 at 04:09
Does this need to be time and space efficient or are there not many items in this list? — Mike, Nov 15 '19 at 04:10
Possible duplicate of [Sorting list of lists by the first element of each sub-list](https://stackoverflow.com/questions/36955553/sorting-list-of-lists-by-the-first-element-of-each-sub-list) — pyeR_biz, Nov 15 '19 at 04:18

score 2 · Accepted Answer · answered Nov 15 '19 at 04:14

2

First of all don't use list as variable name as it is one of python built-in function, and second you can use sorted function to sort by position

l = []
l.append([1, 2, 3])
l.append([1, 1, 1])
l.append([1, 3, 2])
sorted(l,key = lambda x : x[2])
#[[1, 1, 1], [1, 3, 2], [1, 2, 3]]

answered Nov 15 '19 at 04:14

ExplodingGayFish

2,807
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14

I didn't know about this. Thanks, exactly what I was looking for. – JohnMadden Nov 15 '19 at 04:15
2

`lambda x : x[-1]` will be more general to pick last element – pyeR_biz Nov 15 '19 at 04:17
`l` (el) isn't a good variable name. It looks like a '1' (one) in many fonts. Can use the `operator` library: `my_list.sort(key=operator.itemgetter(-1))` – RootTwo Nov 15 '19 at 04:27

Python sorting arrays by element contained?

1 Answers1