Added levenshtein distance

plugins/FunCommands.py

@@ -56,6 +56,7 @@ Commands include:
   last
   lastfrom
   lithp
+  levenshtein
   pydoc
 """
 
@@ -423,6 +424,15 @@ class FunCommands(callbacks.Privmsg):
                 return
         irc.error(msg, 'I don\'t remember a message from that person.')
 
+    def levenshtein(self, irc, msg, args):
+        """<string1> <string2>
+
+        Returns the levenshtein distance (also known as the "edit distance"
+        between <string1> and <string2>
+        """
+        (s1, s2) = privmsgs.getArgs(args, needed=2)
+        irc.reply(msg, str(utils.distance(s1, s2)))
+
     modulechars = '%s%s%s' % (string.ascii_letters, string.digits, '_.')
     def pydoc(self, irc, msg, args):
         """<python function>

src/utils.py

@@ -152,6 +152,26 @@ def timeElapsed(now, then, leadingZeroes=False, years=True, weeks=True,
     else:
         return ' and '.join([', '.join(ret[:-1]), ret[-1]])
         
+def distance(s, t):
+    n = len(s)
+    m = len(t)
+    if n == 0:
+        return m
+    elif m == 0:
+        return n
+    d = range(n+1)
+    for i in range(len(d)):
+        d[i] = range(m+1)
+    for i in range(1, n+1):
+        cs = s[i-1]
+        for j in range(1, m+1):
+            ct = t[j-1]
+            if cs == ct:
+                cost = 0
+            else:
+                cost = 1
+            d[i][j] = min(d[i-1][j]+1, d[i][j-1]+1, d[i-1][j-1]+cost)
+    return d[n][m]
     
 
 # vim:set shiftwidth=4 tabstop=8 expandtab textwidth=78:

test/utils_test.py

@@ -53,3 +53,12 @@ class UtilsTest(unittest.TestCase):
         s = 'foobar'
         L = ['f', 'fo', 'foo', 'foob', 'fooba', 'foobar']
         self.assertEqual(list(utils.eachSubstring(s)), L)
+
+    def testDistance(self):
+        self.assertEqual(utils.distance('', ''), 0)
+        self.assertEqual(utils.distance('a', 'b'), 1)
+        self.assertEqual(utils.distance('a', 'a'), 0)
+        self.assertEqual(utils.distance('foobar', 'jemfinch'), 8)
+        self.assertEqual(utils.distance('a', 'ab'), 1)
+        self.assertEqual(utils.distance('foo', ''), 3)
+        self.assertEqual(utils.distance('', 'foo'), 3)