Fancy indexing in Python

Indexing with arrays of positions, which copies rather than views.

import numpy as np

grid = np.arange(20).reshape(4, 5)

print(grid[[0, 3, 0]])
print(grid[[0, 1, 2], [4, 3, 2]])

scores = np.array([88, 104, 91, 79])
order = np.argsort(scores)[::-1]
print(order, scores[order])
print(np.argmax(scores), np.argmin(scores))

How it works

1. An integer array picks rows in any order, repeats allowed.
2. Two index arrays pick individual elements pairwise.
3. argsort gives the permutation that would sort the array.

Keywords and builtins used here

• as
• print

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Step 2 of 3 in Indexing, step 14 of 22 in NumPy.

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