code :

```
>>> import numpy as np
>>> u_padded = np.random.randint(1,100,3024).reshape(1,3024) # random array of 1*3024 elements
>>> u_padded.shape
(1, 3024)
>>> index = np.random.randint(0,3024,100*2016).reshape(100,2016) # random array of 100*2016 indexes with index range = (0,3024)
>>> index.shape
(100, 2016)
>>> u_padded[0,index] # select elements from u_padded with index from index array
array([[91, 53, 67, ..., 55, 13, 66],
[16, 35, 64, ..., 58, 22, 62],
[67, 36, 70, ..., 22, 53, 94],
...,
[28, 49, 61, ..., 89, 74, 8],
[81, 34, 98, ..., 72, 70, 25],
[16, 77, 27, ..., 42, 80, 45]])
>>> u_padded[0,index].shape
(100, 3024)
```