Menu
How can I index the last axis of a Numpy array if I don't know its rank in advance?
Here is what I want to do: Let a be a Numpy array of unknown rank. I want the slice of the last k elements of the last axis.
If a is 1D, I want
b = a[-k:]
If a is 2D, I want
b = a[:, -k:]
If a is 3D, I want
b = a[:, :, -k:]
and so on.
I want this to work regardless of the rank of a (as long as the rank is at least 1).
The fact that I want the last k elements in the example is irrelevant of course, the point is that I want to specify indices for whatever the last axis is when I don't know the rank of an array in advance.
802
Slice One-dimensional Numpy Arrays If you to select the last element of the array, you can use index [11] , as you know that indexing in Python begins with [0] .
Fancy indexing is conceptually simple: it means passing an array of indices to access multiple array elements at once. For example, consider the following array: import numpy as np rand = np. random. RandomState(42) x = rand.
Code. In the example below, the NumPy array is ranked using the argsort() method. The ranks[temp] = np. arange(len(array)) function is used to rank every element in the array.
b = a[..., -k:]
This is mentioned in the docs.
115
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
