How to remove all rows in a numpy ndarray that contain non numeric values?

Given a NumPy ndarray, we have to remove all rows in a numpy ndarray that contain non numeric values. By Pranit Sharma Last updated : October 09, 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 with a ndarray with 3 rows out of which 1 row contains some non-numeric value and we need to remove this row from this numpy array.

Removing all rows in a numpy ndarray that contain non numeric values

For this purpose, we will use the isnan() method. The np.isnan(arr) returns a similar array with True where NaN, False elsewhere.

Along with this method, we will use any(axis=1) method which reduces an m*n array to n with an logical or operation on the whole rows, ~ (tilde sign) inverts True/False and arr[] chooses just the rows from the original array, which have True within the brackets.

Let us understand with the help of an example,

Python program to remove all rows in a numpy ndarray that contain non numeric values

# Import numpy
import numpy as np

# Creating an array
arr = np.array([[1,2,3], [4,5,np.nan], [7,8,9]])

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

# Removing rows having nan value
res = arr[~np.isnan(arr).any(axis=1)]

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