I was wondering how I would be able to sort a whole array by the values in one of its columns.

I have :

array([5,2,8,2,4])

and:

array([[ 0,  1,  2,  3,  4],[ 5,  6,  7,  8,  9],[10, 11, 12, 13, 14],[15, 16, 17, 18, 19],[20, 21, 22, 23, 24]])

I want to append the first array to the second one like this:

array([[ 0,  1,  2,  3,  4],[ 5,  6,  7,  8,  9],[10, 11, 12, 13, 14],[15, 16, 17, 18, 19],[20, 21, 22, 23, 24],[5,  2,  8,  2,  4]])

And then sort the array by the appended row to get either this:

array([[1,  3,  4,  0,  2],[6,  8,  9,  5,  7],[11, 13, 14, 10, 12],[16, 18, 19, 15, 17],[21, 23, 24, 20, 22],[2,  2,  4,  5,  8]])

or this:

array([[ 2,  1,  3,  4,  0],[ 7,  6,  8,  9,  5],[12, 11, 13, 14, 10],[17, 16, 18, 19, 15],[22, 21, 23, 24, 20],[ 8,  5,  4,  2,  2]])

And then remove the appended column to get:

array([[1,  3,  4,  0,  2],[6,  8,  9,  5,  7],[11, 13, 14, 10, 12],[16, 18, 19, 15, 17],[21, 23, 24, 20, 22]])

or:

array([[ 2,  1,  3,  4,  0],[ 7,  6,  8,  9,  5],[12, 11, 13, 14, 10],[17, 16, 18, 19, 15],[22, 21, 23, 24, 20]])

Is there a code to carry out this procedure. I am very new to python. Thanks a lot!

You can use numpy.argsort to get a list with the sorted indices of your array. Using that you can then rearrange the columns of the matrix.

import numpy as npc = np.array([5,2,8,2,4])    
a = np.array([[ 0,  1,  2,  3,  4],[ 5,  6,  7,  8,  9],[10, 11, 12, 13, 14],[15, 16, 17, 18, 19],[20, 21, 22, 23, 24]])i = np.argsort(c)
a = a[:,i]