Sort array by specific column then sort by value of this column

Question

I'm currently learning Python and I'm trying to sort an array. As the title is problably not very specific I'm gonna give an exemple of what I'm tring to do : I have an array like that :

a = array([[1, 2], [0, 5], [0, 3], [1, 0]])

But with much more rows and higher numbers and I would like that :

a = array([[0, 3], [0, 5], [1, 0], [1, 2]])

For the moment I managed to obtain this :

a = array([[0, 5], [0, 3], [1, 5], [1, 0]])

by using a = a[a[:, 0].argsort()]

But I'm stuck there and I haven't found help for my problem anywhere and I don't have any idea how to procede...

Could anyone help me please ?

Dani Mesejo · Accepted Answer · 2020-03-24 14:15:18Z

1

You could use the built-in function sorted:

import numpy as np

a = np.array([[1, 2],
           [0, 5],
           [0, 3],
           [1, 0]])


result = np.array(sorted(a, key=tuple))

print(result)

Output

[[0 3]
 [0 5]
 [1 0]
 [1 2]]

answered Mar 24, 2020 at 14:15

Dani Mesejo

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1 Comment

Rocky Over a year ago

This is exactly what I was looking for, thank you so much !

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