Needs reworking

evolve_text.py

@@ -92,7 +92,28 @@ def get_text(self):
 # Genetic operators
 # -----------------------------------------------------------------------------
 
-# TODO: Implement levenshtein_distance function (see Day 9 in-class exercises)
+def levenshtein_distance(message, goal):
+    if len(message) < len(goal):
+        return levenshtein_distance(goal, message)
+    #always uses the shorter string as the indicator for how many
+    #steps it will take to get from one to another
+    if len(goal) == 0:
+        return len(message)
+    #if the length of the goal is = 0, then we just have to see
+    #how long the message is and delete every letter 1 at a time
+    previous_row = range(len(goal) + 1)
+    for index, counter in enumerate(message):
+        current_row = [index + 1]
+        for index2, counter2 in enumerate(goal):
+            dels = current_row[index2] + 1
+            ins = previous_row[index2 + 1] + 1
+            subs = previous_row[index2] + (counter != counter2)
+            current_row.append(min(dels, ins, subs))
+            #finds the minimum amount of steps to the goal.
+        previous_row = current_row
+
+    return previous_row[-1]
+
 # HINT: Now would be a great time to implement memoization if you haven't
 
 def evaluate_text(message, goal_text, verbose=VERBOSE):
@@ -121,15 +142,41 @@ def mutate_text(message, prob_ins=0.05, prob_del=0.05, prob_sub=0.05):
     """
 
     if random.random() < prob_ins:
-        # TODO: Implement insertion-type mutation
-        pass
+        r = random.randint(1, len(message)-1)
+        message = message[:r] + random.choice(VALID_CHARS) + message[r:]
+        #cuts the string randomly and inserts a random valid character
+    if random.random() < prob_del:
+        r2 = random.randint(1, len(message)-1)
+        message = message[:r2 - 1] + message[r2:]
+        #gets a random number between the string and removes that letter
+    if random.random() < prob_sub:
+        r3 = random.randint(1, len(message)-1)
+        message = message[:r3 - 1] + random.choice(VALID_CHARS) + message[r3:]
+        #finds a random character within the string and replaces that character
+        #with a random character
+
 
-    # TODO: Also implement deletion and substitution mutations
     # HINT: Message objects inherit from list, so they also inherit
     #       useful list methods
     # HINT: You probably want to use the VALID_CHARS global variable
 
-    return (message, )   # Length 1 tuple, required by DEAP
+    return (Message("".join(message)), )   # Length 1 tuple, required by DEAP
+
+def mate_text(parent1, parent2):
+    newstring1 = []
+    newstring2 = []
+    index = 0
+    crossover_prob = 0.50
+    # 1/2 chance of characters swapping
+    while index < len(parent1) and index < len(parent2):
+        if random.random() > crossover_prob:
+            newstring1.append(parent2[index])
+            newstring2.append(parent1[index])
+        else:
+            newstring1.append(parent1[index])
+            newstring2.append(parent2[index])
+        index = index + 1
+    return (Message("".join(newstring1)), Message("".join(newstring2)))
 
 
 # -----------------------------------------------------------------------------
@@ -149,7 +196,7 @@ def get_toolbox(text):
 
     # Genetic operators
     toolbox.register("evaluate", evaluate_text, goal_text=text)
-    toolbox.register("mate", tools.cxTwoPoint)
+    toolbox.register("mate", mate_text)
     toolbox.register("mutate", mutate_text)
     toolbox.register("select", tools.selTournament, tournsize=3)
 

results.txt

@@ -0,0 +1,5 @@
+I apologize in advance for not being able to completely debug my code. I could not find the error within
+the sections that I was supposed to implement. Maybe I modified the the Message class in my code when I wasn't supposed to.
+Because the submission date is tonight, I won't be able to debug my code, but each independent section works as implied and
+I will revise this for the future.
+