Merge pull request #1 from sjg21010/Implementation

Implementation-Merge-1

Levenshtein_Edit_Distance.py

@@ -0,0 +1,24 @@
+def edit_distance(str1, str2): #input is 2 strings that we will be comparing
+
+  # create a matrix that has length str2 + 1 columns and length str1 + 1 rows
+  D = [[0 for i in range(len(str2)+1)] for j in range(len(str1)+1)]
+
+  #initialize first row - how many deletions are needed to get an empty list
+  for i in range(len(str1)+1):
+    D[i][0] = i
+
+  #initialize first column - how many insertions to go from empty list to str2
+  for j in range(len(str2)+1):
+    D[0][j] = j
+
+  #fill in rest of matrix with recursive case
+  for i in range(1, len(str1)+1):
+    for j in range(1, len(str2)+1):
+      if str1[i-1] == str2[j-1]:
+        cost = 0  #match: no operation needed
+      else:
+        cost = 1  #no match: substitution
+      D[i][j] = min(D[i-1][j] + 1, D[i][j-1] + 1,D[i-1][j-1] + cost)
+
+    return D[len(str1)][len(str2)] #last cell of matrix contains optimal solution
+