Hello everyone!
I am having trouble with genetic programming. I am trying to construct
a random population of trees representing functions. The following is
how I do my random trees:
(defn makerandomtree-10
[pc maxdepth maxwidth fpx ppx]
(if-let [output
(if (and (< (rand) fpx) (> maxdepth 0))
(let [head (nth operations (rand-int (count operations)))
children (doall (loop[function (list)
width maxwidth]
(if (pos? width)
(recur (concat function
(list (makerandomtree-10 pc (dec maxdepth)
(+ 2 (rand-int (- maxwidth 1))) fpx ppx)))
(dec width))
function)))]
(concat (list head) children))
(if (and (< (rand) ppx) (>= pc 0))
(nth parameters (rand-int (count parameters)))
(rand-int 100)))]
output
))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
And it works. The thing that doesn't work is mutation. I have already
done 10 versions of this, and all doesn't work good enough. The
following is the thing that works the best, but not really good
enough.
(defn mutate-5
"chooses a node changes that"
[function pc maxwidth pchange]
(if (< (rand) pchange)
(let [output (makerandomtree-10 pc 3 maxwidth 0.5 0.6)]
(if (seq? output) output (list output)))
;mutate the children of root
;declare an empty accumulator list, with root as its head
(let [head (list (first function))
children (loop [acc(list)
walker (next function)] (println "----------")
(println
walker) (println "-----ACC-----") (println acc)
(if (not walker)
acc
(if (or (seq? (first function)) (contains? (set
operations)
(first function)))
(recur (concat acc (mutate-5 walker pc
maxwidth pchange))
(next walker))
(if (< (rand) pchange)
(if (some (set parameters) walker)
(recur (concat acc (list (nth
parameters (rand-int (count
parameters)))))
(if (seq? walker) (next walker)
nil))
(recur (concat acc (list (rand-int
100)))
(if (seq? walker) (next walker)
nil)))
(recur acc (if (seq? walker) (next walker)
nil))))
))]
(concat head (list children)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
I am sorry that it is somewhat obfuscated. As you can see, I am a
newbie to clojure, and to functional programming in general.
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