genetic

commit 47bc5d08c726253078ee45d20479ddaa26353549
parent e700eba136d4dabc9a9bbe120247e78bb2f913b5
Author: dracuxan <[email protected]>
Date:   Wed,  8 Apr 2026 17:07:05 +0530

new: custom mutation methods

Diffstat:
M
genetic/lib/genetic.ex
 | 
9
++++++---
A
genetic/lib/toolbox/mutation.ex
 | 
68
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
genetic/scripts/codebreaker.exs
 | 
33
++++++++++++++++++---------------
M
genetic/scripts/one_max.exs
 | 
3
++-

4 files changed, 94 insertions(+), 19 deletions(-)
diff --git a/genetic/lib/genetic.ex b/genetic/lib/genetic.ex
@@ -66,11 +66,14 @@ defmodule Genetic do
     )
   end
 
-  def mutation(population, _opts \\ []) do
+  def mutation(population, opts \\ []) do
+    mutation_fn = Keyword.get(opts, :mutation_type, &Toolbox.Mutation.gaussian/2)
+    mutation_rate = Keyword.get(opts, :mutation_rate, 0.05)
+
     population
     |> Enum.map(fn chromosome ->
-      if :rand.uniform() < 0.05 do
-        %Chromosome{chromosome | genes: Enum.shuffle(chromosome.genes)}
+      if :rand.uniform() < mutation_rate do
+        apply(mutation_fn, [chromosome, opts])
       else
         chromosome
       end
diff --git a/genetic/lib/toolbox/mutation.ex b/genetic/lib/toolbox/mutation.ex
@@ -0,0 +1,68 @@
+defmodule Toolbox.Mutation do
+  alias Types.Chromosome
+
+  def flip(chromosome, _opts \\ []) do
+    genes =
+      chromosome.genes
+      |> Enum.map(&Bitwise.bxor(&1, 1))
+
+    %Chromosome{genes: genes, size: chromosome.size}
+  end
+
+  def flip_some(chromosome, opts \\ []) do
+    p = Keyword.get(opts, :p, 0.5)
+
+    genes =
+      chromosome.genes
+      |> Enum.map(fn g ->
+        if :rand.uniform() < p do
+          Bitwise.bxor(g, 1)
+        else
+          g
+        end
+      end)
+
+    %Chromosome{genes: genes, size: chromosome.size}
+  end
+
+  def scramble(chromosome, _opts \\ []) do
+    genes =
+      chromosome.genes
+      |> Enum.shuffle()
+
+    %Chromosome{genes: genes, size: chromosome.size}
+  end
+
+  def scramble_n(chromosome, _opts \\ []) do
+    n = 10
+    start = :rand.uniform(n - 1)
+
+    {lo, hi} =
+      if start + n >= chromosome.size do
+        {start - n, start}
+      else
+        {start, start + n}
+      end
+
+    head = Enum.slice(chromosome.genes, 0, lo)
+    mid = Enum.slice(chromosome.genes, lo, hi) |> Enum.shuffle()
+    tail = Enum.slice(chromosome.genes, hi, chromosome.size)
+    %Chromosome{genes: head ++ mid ++ tail, size: chromosome.size}
+  end
+
+  def gaussian(chromosome, _opts \\ []) do
+    mu = Enum.sum(chromosome.genes) / length(chromosome.genes)
+
+    sigma =
+      chromosome.genes
+      |> Enum.map(fn x -> (mu - x) * (mu - x) end)
+      |> Enum.sum()
+      |> Kernel./(length(chromosome.genes))
+
+    genes =
+      chromosome.genes
+      |> Enum.map(fn _ -> :rand.normal(mu, sigma) end)
+
+    %Chromosome{genes: genes, size: chromosome.size}
+  end
+end
diff --git a/genetic/scripts/codebreaker.exs b/genetic/scripts/codebreaker.exs
@@ -10,8 +10,8 @@ defmodule Codebreaker do
   end
 
   def fitness_function(chromosome) do
-    target = "ILoveGeneticAlgorithms"
-    encrypted = "LIjs`B`k`qlfDibjwlqmhv"
+    target = "dracuxan"
+    encrypted = "awdfp}dk"
 
     cypher = fn word, key ->
       word
@@ -19,12 +19,7 @@ defmodule Codebreaker do
       |> Enum.map(fn x -> rem(bxor(x, key), 32768) end)
     end
 
-    key =
-      chromosome.genes
-      |> Enum.map(&Integer.to_string(&1))
-      |> Enum.join("")
-      |> String.to_integer(2)
-
+    key = generate_integer_key(chromosome.genes)
     guess = List.to_string(cypher.(encrypted, key))
     String.jaro_distance(target, guess)
   end
@@ -33,14 +28,22 @@ defmodule Codebreaker do
     best = hd(population)
     best.fitness == 1
   end
+
+  def generate_integer_key(key) do
+    key
+    |> Enum.map(&Integer.to_string(&1))
+    |> Enum.join("")
+    |> String.to_integer(2)
+  end
 end
 
-{soln, _} = Genetic.run(Codebreaker, crossover_type: &Toolbox.Crossover.single_point/3)
+{soln, generation} =
+  Genetic.run(
+    Codebreaker,
+    crossover_type: &Toolbox.Crossover.single_point/3,
+    mutation_type: &Toolbox.Mutation.flip_some/2
+  )
 
-{key, ""} =
-  soln.genes
-  |> Enum.map(&Integer.to_string(&1))
-  |> Enum.join("")
-  |> Integer.parse(2)
+key = Codebreaker.generate_integer_key(soln.genes)
 
-IO.puts("\nThe key is #{key}")
+IO.puts("\nkey: #{key}\ngenerations passed: #{generation}")
diff --git a/genetic/scripts/one_max.exs b/genetic/scripts/one_max.exs
@@ -38,7 +38,8 @@ end
   Genetic.run(
     OneMax,
     selection_type: &Toolbox.Selection.elite/2,
-    crossover_type: &Toolbox.Crossover.uniform/3
+    crossover_type: &Toolbox.Crossover.uniform/3,
+    mutation_type: &Toolbox.Mutation.gaussian/2
   )
 
 IO.puts("\nfinal answer: #{inspect(soln)}")