Finding if two strings are almost similar

Question

I want to find out if you strings are almost similar. For example, string like \'Mohan Mehta\' should match \'Mohan Mehte\' and vice versa. Another example, string like \'Um

Answer 1

What you want is a string distance. There many flavors, but I would recommend starting with the Levenshtein distance.

Answer 2

You can use difflib.sequencematcher if you want something from the stdlib:

from difflib import SequenceMatcher
s_1 = 'Mohan Mehta'
s_2 = 'Mohan Mehte'
print(SequenceMatcher(a=s_1,b=s_2).ratio())
0.909090909091

fuzzywuzzy is one of numerous libs that you can install, it uses the difflib module with python-Levenshtein. You should also check out the wikipage on Approximate_string_matching

Answer 3

you might want to look at NLTK (The Natural Language Toolkit), specifically the nltk.metrics package, which implements various string distance algorithms, including the Levenshtein distance mentioned already.

Answer 4

You could split the string and check to see if it contains at least one first/last name that is correct.

Answer 5

Another approach is to use a "phonetic algorithm":

A phonetic algorithm is an algorithm for indexing of words by their pronunciation.

For example using the soundex algorithm:

>>> import soundex
>>> s = soundex.getInstance()
>>> s.soundex("Umesh Gupta")
'U5213'
>>> s.soundex("Umash Gupte")
'U5213'
>>> s.soundex("Umesh Gupta") == s.soundex("Umash Gupte")
True

Answer 6

// calculate the similarity between 2 strings

  public static double similarity(String s1, String s2) {
    String longer = s1, shorter = s2;
    if (s1.length() < s2.length()) { // longer should always have greater length
      longer = s2; shorter = s1;
    }
    int longerLength = longer.length();
    if (longerLength == 0) { return 1.0; /* both strings are zero length */ }
    /* // If you have StringUtils, you can use it to calculate the edit distance:
    return (longerLength - StringUtils.getLevenshteinDistance(longer, shorter)) /
                               (double) longerLength; */
    return (longerLength - editDistance(longer, shorter)) / (double) longerLength;

  }

  // Example implementation of the Levenshtein Edit Distance
  // See http://rosettacode.org/wiki/Levenshtein_distance#Java
  public static int editDistance(String s1, String s2) {
    s1 = s1.toLowerCase();
    s2 = s2.toLowerCase();

    int[] costs = new int[s2.length() + 1];
    for (int i = 0; i <= s1.length(); i++) {
      int lastValue = i;
      for (int j = 0; j <= s2.length(); j++) {
        if (i == 0)
          costs[j] = j;
        else {
          if (j > 0) {
            int newValue = costs[j - 1];
            if (s1.charAt(i - 1) != s2.charAt(j - 1))
              newValue = Math.min(Math.min(newValue, lastValue),
                  costs[j]) + 1;
            costs[j - 1] = lastValue;
            lastValue = newValue;
          }
        }
      }
      if (i > 0)
        costs[s2.length()] = lastValue;
    }
    return costs[s2.length()];
  }