Data commit

Task/Evolutionary-algorithm/Ring/evolutionary-algorithm.ring

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+# Project : Evolutionary algorithm
+
+target = "METHINKS IT IS LIKE A WEASEL"
+parent = "IU RFSGJABGOLYWF XSMFXNIABKT"
+num = 0
+mutationrate = 0.5
+children = len(target)
+child = list(children)
+while parent != target
+        bestfitness = 0
+        bestindex = 0
+        for index = 1 to children
+             child[index] = mutate(parent, mutationrate)
+             fitness = fitness(target, child[index])
+             if fitness > bestfitness
+                bestfitness = fitness
+                bestindex = index
+             ok
+        next
+        if bestindex > 0
+           parent = child[bestindex]
+           num = num + 1
+           see "" + num + ": " + parent + nl
+        ok
+end
+
+func fitness(text, ref)
+       f = 0
+       for i = 1 to len(text)
+            if substr(text, i, 1) = substr(ref, i, 1)
+               f = f + 1
+            ok
+       next
+       return (f / len(text))
+
+func mutate(text, rate)
+        rnd = randomf()
+        if rate > rnd
+           c = 63+random(27)
+           if c = 64
+              c = 32
+           ok
+           rnd2 = random(len(text))
+           if rnd2 > 0
+              text[rnd2] = char(c)
+           ok
+        ok
+        return text
+
+func randomf()
+       decimals(10)
+       str = "0."
+       for i = 1 to 10
+            nr = random(9)
+            str = str + string(nr)
+       next
+       return number(str)