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Get the first index of an elements in a NumPy array

In this tutorial, we will learn how to get the first index of an elements in a NumPy array? By Pranit Sharma Last updated : May 23, 2023

Problem statement

Suppose we are given a NumPy array with some values and we are given the specified item to search for.

Getting the first index of an elements in a NumPy array

To Get the first index of an elements in a NumPy array, you can use numpy.where() by passing arr == item, where arr is NumPy array and item is the value whose index to be found.

The result of this expression would be a tuple with first all the row indices, then all the column indices.

Let us understand with the help of an example,

Python program to get the first index of an elements in a NumPy array

# Import numpy
import numpy as np

# Creating a numpy array
arr = np.array([0, 3, 0, 1, 0, 1, 2, 1, 0, 0, 0, 0, 1, 3, 4])

# Specifying an item to search
item = 3

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

# Using numpy.where
index = np.where(arr == item)

# Display Result
print('Result:\n',index)

Output

The output of the above program is:

Original Array:
 [0 3 0 1 0 1 2 1 0 0 0 0 1 3 4] 

Result:
 (array([ 1, 13]),)
 

Output (Screenshot)

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