enumerate()

Let's enumerate! Your task is, given a string, to define the function retrieve_character_indices() that creates a dictionary character_indices, where each key represents a unique character from the string and the corresponding value is a list containing the indices/positions of this letter in the string.

For example, passing the string 'ukulele' to the retrieve_character_indices() function should result in the following output: {'e': [4, 6], 'k': [1], 'l': [3, 5], 'u': [0, 2]}.

For this task, you are not allowed to use any string methods!

This exercise is part of the course

Practicing Coding Interview Questions in Python

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Exercise instructions

Define the for loop that iterates over the characters in the string and their indices.
Update the dictionary if the key already exists.
Update the dictionary if the key is absent.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

def retrieve_character_indices(string):
    character_indices = dict()
    # Define the 'for' loop
    for index, character in ____(____):
        # Update the dictionary if the key already exists
        if character in character_indices:
            ____[____].____(____)
        # Update the dictionary if the key is absent
        else:
            ____[____] = [____]
            
    return character_indices
  
print(retrieve_character_indices('enumerate an Iterable'))

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