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 standar

Answer 1

There are many metrics to define similarity and distance between strings as mentioned above. I will give my 5 cents by showing an example of Jaccard similarity with Q-Grams and an example with edit distance.

The libraries

from nltk.metrics.distance import jaccard_distance
from nltk.util import ngrams
from nltk.metrics.distance  import edit_distance

Jaccard Similarity

1-jaccard_distance(set(ngrams('Apple', 2)), set(ngrams('Appel', 2)))

and we get:

0.33333333333333337

And for the Apple and Mango

1-jaccard_distance(set(ngrams('Apple', 2)), set(ngrams('Mango', 2)))

and we get:

0.0

Edit Distance

edit_distance('Apple', 'Appel')

and we get:

2

And finally,

edit_distance('Apple', 'Mango')

and we get:

5

Cosine Similarity on Q-Grams (q=2)

Another solution is to work with the textdistance library. I will provide an example of Cosine Similarity

import textdistance
1-textdistance.Cosine(qval=2).distance('Apple', 'Appel')

and we get:

0.5