Development - Advanced, exercise 27

Text

The Quick Gestalt Pattern Matching is a statistic used for comparing the similarity of two strings. In particular, given two strings S and T, the measure is calculated by considering twice the number K_m of all used characters in S which occur in T divided by the sum of the number of characters in S and T:

  2 * Km
---------
|S| + |T|

Write an algorithm in Python – def qgpm(s, t) – which takes in input two strings and returns the Gestalt Pattern Matching statistic.

Solution

# Test case for the function
def test_qgpm(s, t, expected):
    result = qgpm(s, t)
    if expected == result:
        return True
    else:
        return False


# Code of the function
def qgpm(s, t):
    common = 0
    t_list = list(t)

    for c in s:
        if c in t_list:
            common += 1
            t_list.remove(c)
        
    return (2 * common) / (len(s) + len(t))


# Tests
print(test_qgpm("ciao", "ciao", 1))
print(test_qgpm("mummy", "my", 4 / 7))
print(test_qgpm("m", "mummy", 2 / 6))

Additional material

The runnable Python file is available online.