Python: Find the indexes of all elements in the given list that satisfy the provided testing function

Last update on April 19 2025 13:01:06 (UTC/GMT +8 hours)

All Indices Satisfying Function

Write a Python program to find the indexes of all elements in the given list that satisfy the provided testing function.

Use enumerate() and a list comprehension to return the indexes of the all element in lst for which fn returns True.

Sample Solution:

Python Code:

# Define a function 'find_index_of_all' that takes a list 'lst' and a function 'fn' as input.
def find_index_of_all(lst, fn):
    # Use a list comprehension to find and collect the indices 'i' where 'fn(x)' is True for an element 'x' in 'lst'.
    return [i for i, x in enumerate(lst) if fn(x)]

# Call the 'find_index_of_all' function with an example list and a lambda function that checks if a number is odd.
print(find_index_of_all([1, 2, 3, 4], lambda n: n % 2 == 1)) 

Sample Output:

[0, 2]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to find all indices of elements in a list that satisfy a given predicate and return them in sorted order.
• Write a Python program to retrieve the indices of all even numbers in a list using a provided testing function.
• Write a Python program to find all indices of elements that are prime numbers in a list and count the total occurrences.
• Write a Python program to extract and display the indices of all list elements that satisfy a custom lambda function.

Python Code Editor:

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