Data commit

Task/Evolutionary-algorithm/Python/evolutionary-algorithm-2.py

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+from random import choice, random
+
+target  = list("METHINKS IT IS LIKE A WEASEL")
+alphabet = " ABCDEFGHIJLKLMNOPQRSTUVWXYZ"
+p = 0.05 # mutation probability
+c = 100  # number of children in each generation
+
+def neg_fitness(trial):
+    return sum(t != h for t,h in zip(trial, target))
+
+def mutate(parent):
+    return [(choice(alphabet) if random() < p else ch) for ch in parent]
+
+parent = [choice(alphabet) for _ in xrange(len(target))]
+i = 0
+print "%3d" % i, "".join(parent)
+while parent != target:
+    copies = (mutate(parent) for _ in xrange(c))
+    parent = min(copies, key=neg_fitness)
+    print "%3d" % i, "".join(parent)
+    i += 1