Python: Map dictionary

Last update on June 28 2025 12:39:51 (UTC/GMT +8 hours)

70. Map List Values to Dictionary Using a Function

Write a Python program to map the values of a given list to a dictionary using a function, where the key-value pairs consist of the original value as the key and the result of the function as the value.

Use map() to apply fn to each value of the list.
Use zip() to pair original values to the values produced by fn.
Use dict() to return an appropriate dictionary.

Sample Solution:

Python Code:

# Define a function 'test' that takes two arguments: 'itr' (an iterable) and 'fn' (a function).
def test(itr, fn):
    # Use the 'zip' function to pair each element from 'itr' with the result of applying 'fn' to that element.
    # Convert the zipped pairs into a dictionary where the elements from 'itr' are keys, and the results of 'fn' are values.
    return dict(zip(itr, map(fn, itr)))

# Call the 'test' function with an iterable [1, 2, 3, 4] and a lambda function that squares its input.
# The lambda function calculates the square of each element in the iterable.
result = test([1, 2, 3, 4], lambda x: x * x)

# Print the resulting dictionary.
print(result)

Sample Output:

{1: 1, 2: 4, 3: 9, 4: 16}

Flowchart:

Flowchart: Map dictionary.

For more Practice: Solve these Related Problems:

Write a Python program to convert a list of numbers into a dictionary where each key is the number and its value is the square of the number.
Write a Python program to map a list of strings to a dictionary where each key is the string and the value is its length.
Write a Python program to implement a function that takes a list and a function, returning a dictionary mapping each element to the function’s result.
Write a Python program to use dictionary comprehension to map each element of a list to its factorial value.

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