python how sort works on 2d array code example

Example 1: sort by index 2d array python

a = [[9, 9, 2], [9, 9, 3], [9, 9, 8], [9, 9, 4], [9, 9, 1], [9, 9, 5]]

b = sorted(a, key=lambda a:a[2])

#b contains the following arrays, sorted by their second index:
[[9, 9, 1], [9, 9, 2], [9, 9, 3], [9, 9, 4], [9, 9, 5], [9, 9, 8]]

Example 2: python order 2d array by secode element

sorted(arr, key=lambda x: x[1])