w3resource

Select elements from 2D NumPy array with random floats using Boolean indexing

NumPy: Advanced Indexing Exercise-5 with Solution

Boolean Indexing with Conditions:

Write a NumPy program that creates a 2D NumPy array of random floats and uses boolean indexing to select elements that satisfy multiple conditions (e.g., greater than 0.5 and less than 0.8).

Sample Solution:

Python Code:

import numpy as np

# Create a 2D NumPy array of random floats between 0 and 1
array_2d = np.random.rand(5, 5)

# Define the conditions
condition1 = array_2d > 0.5
condition2 = array_2d < 0.8

# Use boolean indexing to select elements that satisfy both conditions
selected_elements = array_2d[condition1 & condition2]

# Print the original array and the selected elements
print('Original 2D array:\n', array_2d)
print('Elements greater than 0.5 and less than 0.8:\n', selected_elements)

Output:

Original 2D array:
 [[0.52972276 0.70225957 0.27440778 0.18107896 0.11912977]
 [0.38789867 0.55283666 0.92619903 0.45360212 0.30341309]
 [0.96337533 0.11772659 0.57502825 0.6581205  0.40238651]
 [0.21598097 0.58864959 0.83392972 0.26703946 0.57283874]
 [0.67218407 0.19983269 0.23111841 0.24815625 0.22444408]]
Elements greater than 0.5 and less than 0.8:
 [0.52972276 0.70225957 0.55283666 0.57502825 0.6581205  0.58864959
 0.57283874 0.67218407]

Explanation:

  • Import libraries:
    • Imported numpy as np for array creation and manipulation.
  • Create 2D NumPy Array:
    • Create a 2D NumPy array named array_2d with random floats between 0 and 1 using np.random.rand.
  • Define the conditions:
    • Defined two conditions: condition1 to check if elements are greater than 0.5, and condition2 to check if elements are less than 0.8.
  • Boolean Indexing:
    • Applied boolean indexing to select elements that satisfy both conditions using the & operator to combine them.
  • Print Results:
    • Print the original 2D array and the elements that satisfy both conditions to verify the indexing operation.

Python-Numpy Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.

Previous: Select a Subarray from 4D NumPy array using Multi-dimensional indexing.
Next: Select elements from 2D NumPy array using integer Indexing.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Become a Patron!

Follow us on Facebook and Twitter for latest update.

It will be nice if you may share this link in any developer community or anywhere else, from where other developers may find this content. Thanks.

https://198.211.115.131/python-exercises/numpy/select-elements-from-2d-numpy-array-with-random-floats-using-boolean-indexing.php