Assessment Questions: Numpy Arrays

Novice from Competent

Given the 2D array generated using the following code snippet:

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import numpy as np
x = np.random.normal(size=(10,10))
y = x[2:5,1:5]
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What is the shape of y?

1. (4,5)
2. (3,3)
3. (3,4)
4. (5,4)
5. (4,3)

Expert from Competent

Suppose you had an array generated by the following code:

x = np.arange(25).reshape((5,5))

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]])


Which of the following commands would give you the following array?

array([[ 1, 4],
[ 6, 9],
[21, 24]])


1. x[[0,1,4],[1,4]]
2. x[np.ix_([0,1,4],[1,4])]
3. x[np.meshgrid([0,1,4],[1,4])]
4. x[[0,1,4]][1,4]
5. x[[0,1,4]][[1,4],:]