langs a-z

Task/Evolutionary-algorithm/Pike/evolutionary-algorithm.pike

@@ -0,0 +1,44 @@
+string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ ";
+
+string mutate(string data, int rate)
+{
+    array(int) alphabet=(array(int))chars;
+    multiset index = (multiset)enumerate(sizeof(data));
+    while(rate)
+    {
+        int pos = random(index);
+        data[pos]=random(alphabet);
+        rate--;
+    }
+    return data;
+}
+
+int fitness(string input, string target)
+{
+    return `+(@`==(((array)input)[*], ((array)target)[*]));
+}
+
+void main()
+{
+    array(string) alphabet = chars/"";
+    string target = "METHINKS IT IS LIKE A WEASEL";
+    string parent = "";
+
+    while(sizeof(parent) != sizeof(target))
+    {
+        parent += random(alphabet);
+    }
+
+    int count;
+    write(" %5d: %s\n", count, parent);
+    while (parent != target)
+    {
+        string child = mutate(parent, 2);
+        count++;
+        if (fitness(child, target) > fitness(parent, target))
+        {
+            write(" %5d: %s\n", count, child);
+            parent = child;
+        }
+    }
+}