Python Sort Multidimensional Array

Question

I need to sort an array of arrays by a specific element

This is an array:

arr= 
[0, [71, 554, 258, 793]]
[1, [61, 415, 148, 593]]
[2, [91, 145, 658, 893]]

I need to be able to sort it by arr[0][0] as well as by any element from the internal array like arr[0][1] or arr[0][2]

currently, I'm able to sort it by using key=itemgetter(1) where: itemgetter(1) - is second element of array [0, [71, 554, 258, 793]] in this cese = 71

from operator import itemgetter
array = sorted(array, key=itemgetter(1))
print(*array[:], sep="\n")

how to sort this array by any element from the internal array [71, 554, 258, 793]?

so if I'm sorting by the second element from internal array output should be like this: (column 145, 415, 554)

arr= 
[2, [91, 145, 658, 893]]
[1, [61, 415, 148, 593]]
[0, [71, 554, 258, 793]]

if I'm sorting by the third element from internal array output should be like this: (column 148, 258, 658)

arr= 
[1, [61, 415, 148, 593]]
[0, [71, 554, 258, 793]]
[2, [91, 145, 658, 893]]

this is kinda similar to this question: Python Sort Multidimensional Array Based on 2nd Element of Subarray

How are you stuck with this? You simply replace that 1 constant with a variable that contains the column number. — Prune
– Prune, Commented May 30, 2019 at 23:00
@Prune I wish it would be so straight forward but it's not, u see that index 1 is related to the second element of the first array [A, [B, C, D]] where element 0 = A element 1 is [B, C, D] and there's no element 2 it should be like calling the array element arr[0][2] but this syntax doesn't work in this context with key=itemgetter(1)) — Nick PV
– Nick PV, Commented May 30, 2019 at 23:28

Will · Accepted Answer · 2019-05-30 22:59:00Z

1

Just define a function that decides on the key to use. You can use a partial function to create this function based on the key index

from functools import partial

def sort_key(si, x):
    return x[1][si]

sort_index = 1  # or 1 or 2

partial_sort_key = partial(sort_key, sort_index)

print(sorted(arr, key=partial_sort_key))

answered May 30, 2019 at 22:59

Will

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