String_matching.py

hellogene.py

@@ -0,0 +1,37 @@
+import random, string
+
+GA_POPSIZE = 2048
+GA_ELITRATE= 0.10 # elitism rate
+GA_MUTATIONRATE = 0.25 # mutation rate
+GA_TARGET = "Hello world!"
+GA_CHARS = string.ascii_lowercase + string.digits + string.punctuation + string.whitespace +string.ascii_uppercase
+
+def randstr():
+    return "".join([random.choice(GA_CHARS) for i in range(len(GA_TARGET))])
+
+def fitness(value):
+    return sum([abs(ord(value[j]) - ord(GA_TARGET[j])) for j in range(len(GA_TARGET))])
+
+def mate(population, buffer):
+    esize = int(GA_POPSIZE * GA_ELITRATE)
+    for i in range(esize): # Elitism
+        buffer[i] = population[i]
+    for i in range(esize, GA_POPSIZE):
+        i1 = random.randint(0, GA_POPSIZE / 2)
+        i2 = random.randint(0, GA_POPSIZE / 2)
+        spos = random.randint(0, len(GA_TARGET))
+        buffer[i] = population[i1][:spos] + population[i2][spos:] # Mate
+        if random.random() < GA_MUTATIONRATE: # Mutate
+            pos = random.randint(0, len(GA_TARGET)-1)
+            buffer[i] = buffer[i][:pos] + random.choice(GA_CHARS) + buffer[i][pos+1:]
+
+population = [randstr() for i in range(GA_POPSIZE)]
+buffer = [randstr() for i in range(GA_POPSIZE)]
+while True:
+    i+=1;
+    population = sorted(population, key=lambda c: fitness(c))
+    print (("round: %d variation: %d  string generated:    %s") % (i, fitness(population[0]), population[0]))
+    if not fitness(population[0]): # We're done, best match found
+        break
+    mate(population, buffer)
+    population, buffer = buffer, population