Find the similarity metric between two strings

Question

How do I get the probability of a string being similar to another string in Python?

I want to get a decimal value like 0.9 (meaning 90%) etc. Preferably with standard Python and library.

e.g.

similar("Apple","Appel") #would have a high prob.

similar("Apple","Mango") #would have a lower prob.

Answer 1

There is a built in.

from difflib import SequenceMatcher

def similar(a, b):
    return SequenceMatcher(None, a, b).ratio()

Using it:

>>> similar("Apple","Appel")
0.8
>>> similar("Apple","Mango")
0.0