Inconsistent python print output

Question

(Python 2.7.12) - I have created an NxN array, when I print it I get the exact following output:

Sample a:

SampleArray=np.random.randint(1,100, size=(5,5))    
    [[49 72 88 56 41]
     [30 73  6 43 53]
     [83 54 65 16 34]
     [25 17 73 10 46]
     [75 77 82 12 91]]

• Nice and clean.

However, when I go to sort this array by the elements in the 4th column using the code:

SampleArray=sorted(SampleArray, key=lambda x: x[4])

I get the following output:

Sample b:

[array([90,  9, 77, 63, 48]), array([43, 97, 47, 74, 53]), array([60, 64, 97,  2, 73]), array([34, 20, 42, 80, 76]), array([86, 61, 95, 21, 82])]

How can I get my output to stay in the format of 'Sample a'. It will make debugging much easier if I can see the numbers in a straight column.

Answer 1

Simply with numpy.argsort() routine:

import numpy as np

a = np.random.randint(1,100, size=(5,5))
print(a)   # initial array
print(a[np.argsort(a[:, -1])])  # sorted array

The output for # initial array:

[[21 99 34 33 55]
 [14 81 92 44 97]
 [68 53 35 46 22]
 [64 33 52 40 75]
 [65 35 35 78 43]]

---

The output for # sorted array:

[[68 53 35 46 22]
 [65 35 35 78 43]
 [21 99 34 33 55]
 [64 33 52 40 75]
 [14 81 92 44 97]]