NumPy: Get the index of a maximum element in a numpy array along one axis

Last update on December 21 2024 08:30:15 (UTC/GMT +8 hours)

Get Index of Max Element Along Axis

Write a NumPy program to get the index of a maximum element in a numpy array along one axis.

Sample Solution:

Python Code:

# Importing the NumPy library and aliasing it as 'np'
import numpy as np

# Creating a NumPy array 'a' with given elements arranged in 2x3 shape
a = np.array([[1, 2, 3], [4, 3, 11]])

# Printing a message indicating the original array will be displayed
print("Original array:")

# Displaying the original array 'a'
print(a)

# Using np.unravel_index() to get the indices of the maximum element in the array 'a'
# The argmax() function finds the index of the maximum value in the flattened array
# The unravel_index() function converts this flat index into a tuple of indices for the maximum value's position
i, j = np.unravel_index(a.argmax(), a.shape)

# Printing a message indicating the index of the maximum element in the array along one axis
print("Index of a maximum element in a numpy array along one axis:")

# Displaying the indices of the maximum element in the array 'a'
print(i, j) 

Sample Output:

Original array:
[[ 1  2  3]
 [ 4  3 11]]
1
2
Index of a maximum element in a numpy array along one axis:
12

Explanation:

a = np.array([[1,2,3],[4,3,1]]): Create a 2D NumPy array a with the given values.

i, j = np.unravel_index(a.argmax(), a.shape): The a.argmax() function returns the index of the maximum value in the flattened array. The np.unravel_index() function converts this index into row and column indices (i, j) corresponding to the original shape of the array.

print(a[i, j]): Print the indices of the maximum value in the array.

Pictorial Presentation:

Python-Numpy Code Editor: