How do I cut a square out of a numpy array and create an array out of that?

Question

I want to basically do this:

data = np.arange(25).reshape(5, 5)
print(data)
>> [[ 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]]

Then it would cut it somehow, and I would end up with this

[[6 7 8]
[11 12 13]
[16 17 18]]

I tried using colons but I have no idea how they work, (like data = data(1:3, 4:5))

This is just an extension of basic Python list indexing alist[1:10]. — hpaulj
– hpaulj, Commented Jul 2, 2020 at 15:56

AKX · Accepted Answer · 2020-07-02 15:51:25Z

1

You're on the right track; just use brackets for array subscripting and the same indices for both dimensions of the array:

import numpy as np

data = np.arange(25).reshape(5, 5)
print(data)

print(data[1:4, 1:4])

outputs

[[ 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]]

[[ 6  7  8]
 [11 12 13]
 [16 17 18]]

answered Jul 2, 2020 at 15:51

AKX

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