How to fix ValueError: The truth value of an array with zero elements is ambiguous?

This error arises when you attempt to use an empty array in a conditional context, such as within if-statements or while-loops. This indicates that the truth value of an empty array is ambiguous because it lacks elements to evaluate.

Here is an example code that can produce this error:

import numpy as np

arr = np.array([])
if arr:
    print("The array is not empty")

In this code, the arr variable is an empty NumPy array. When we try to use arr as a condition in the if-statement, the error occurs because there is no value to evaluate.

To resolve this error, ensure the array’s length is greater than zero before utilizing it in a conditional statement:

import numpy as np

arr = np.array([])
if len(arr) > 0:
    print("The array is not empty")

In this code, we first check if the length of the array is greater than zero before using it as a condition in the if-statement. This ensures that the code within the if-block executes only when the array contains elements, preventing the error.