Development - Advanced, exercise 2

Text

The Hamming distance between two strings of equal length is the number of positions at which the corresponding characters are different. Thus, it measures the minimum number of substitutions required to change one string into the other.

Write a Python function which takes two strings as input and that calculates the Hamming distance if the strings have the same length, otherwise it returns the smallest string.

Solution

# Test case for the function
def test_hamming_distance(s1, s2, expected):
    result = hamming_distance(s1, s2)
    if expected == result:
        return True
    else:
        return False


# Code of the function
def hamming_distance(s1, s2):
    if len(s1) < len(s2):
        return s1
    elif len(s1) > len(s2):
        return s2
    else:
        result = 0
        for i in range(len(s1)):
            if s1[i] != s2[i]:
                result = result + 1
        return result


# Tests
print(test_hamming_distance("Silvio", "Peroni", 6))
print(test_hamming_distance("Silvio", "Silvia", 1))
print(test_hamming_distance("Silvio", "Giovanni", "Silvio"))
print(test_hamming_distance("Silvio", "John", "John"))

Additional material

The runnable Python file is available online.