distance module

src/bobbit/modules/distance.py

@@ -0,0 +1,53 @@
+# distance.py
+
+# Metadata
+
+NAME    = 'distance'
+ENABLE  = True
+PATTERN = r'^!distance -s (?P<source>.*) -t (?P<target>.*)'
+USAGE   = '''Usage: !distance -s <source_string> -t <target_string>
+Computes the Levenshtein distance between the source and target strings. Ignores trailing whitespace.
+'''
+
+# Command
+
+def levenshtein(source, target):
+
+    if not source or not target:
+        return 0
+
+    matrix = [[0 for s in range(len(source) + 1)] for t in range(len(target) + 1)]
+
+    for col_ind in range(1, len(source) + 1):
+        matrix[0][col_ind] = col_ind
+    for row_ind in range(1, len(target) + 1):
+        matrix[row_ind][0] = row_ind
+
+    for t in range(1, len(target) + 1):
+        for s in range(1, len(source) + 1):
+
+            if source[s - 1] == target[t - 1]:
+                sub_cost = 0
+            else:
+                sub_cost = 1
+
+            matrix[t][s] = min(matrix[t][s - 1] + 1,
+                                matrix[t - 1][s] + 1,
+                                matrix[t - 1][s - 1] + sub_cost)
+
+    return matrix[-1][-1]
+
+async def distance(bot, message, source, target):
+    source, target = source.rstrip(), target.rstrip()
+    response = f'Levenshtein distance: {levenshtein(source, target)}'
+
+    return message.with_body(response)
+
+# Register
+
+def register(bot)
+    return (
+        ('command', PATTERN, distance)
+    )
+
+# vim: set sts=4 sw=4 ts=8 expandtab ft=python: