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Extracting first n columns of a NumPy matrix
Learn how to extract first n columns of a NumPy matrix in Python?
By Pranit Sharma Last updated : December 28, 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.
Slicing is the technique that will help us to find the first n columns of this numpy array.
NumPy Matrix - Extracting first n columns
Suppose that we are given a multi-dimensional numpy array with certain rows and columns and we just need to extract the first n columns of this numpy array.
Suppose that we have an array a which contains 5 columns and we need to extract its first 3 columns, we will use the following slicing code to extract the first 3 columns: a[: , : , 3]
Let us understand with the help of an example,
Python code to extract first n columns of a NumPy matrix
# Import numpy
import numpy as np
# Creating a numpy array
arr = np.array([[1, 2, 3, 4, 5],
[4, 5, 6, 7, 8],
[7, 8, 9, 10, 11]])
# Display original array
print("Original array:\n",arr,"\n")
# Slicing the array and extracting
# first 3 columns
res = arr[:,:3]
# Display Result
print("Result:\n",res,"\n")
Output
In this example, we have used the following Python basic topics that you should learn:
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