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NumPy: Slice of arbitrary dimensions

Learn, how to slice numpy array of arbitrary dimensions in Python? By Pranit Sharma Last updated : October 10, 2023

NumPy is an abbreviated form of Numerical Python. It is used for different types of scientific operations in python. Numpy is a vast library in python which is used for almost every kind of scientific or mathematical operation. It is itself an array which is a collection of various methods and functions for processing the arrays.

Problem statement

Suppose that we are given a NumPy array and we need to slice this NumPy array to obtain the i^th index in the last dimension.

Slicing NumPy array of arbitrary dimensions

For this purpose, we will use the Ellipsis technique. The ellipsis is used in NumPy to slice high-dimensional data structures. It is designed to mean at this point, insert as many full slices (:) to extend the multi-dimensional slice to all dimensions.

Suppose that we are given a four-dimensional matrix of order 2 X 2 X 2 x 2. To select all the first elements in the fourth dimension we can use the ellipsis notation. Ellipses are also useful for zero-dimensional data structures.

Let us understand with the help of an example,

Python program to slice numpy array of arbitrary dimensions

# Import numpy
import numpy as np

# Creating a numpy array
arr = np.arange(16).reshape(2,2,2,2)

# Display original array
print("Original Array:\n",arr,"\n")

# Using ellipses syntax
res = arr[..., 0].flatten()

# Display result
print("Ellipses syntax result:\n",res,"\n")

Output

The output of the above program is:

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