What would be a good approach to mutate a turtle variable in NetLogo?

Question

I'm simulating a multi-agent system. Each agent has a chromosome. The genotypes represent 5 parameters that are various floating-point numbers between 0 and 100. My mutation operator simply modifies the original gene with a new random number (according to the constant mutation rate). Is that the best approach or could you advise another way? For instance, is that possible to mutate the parameters in a bit digit level to provide more precision?

My mutation operator

Answer 1

Do you mean you'd like to modify the gene value based on its current value, rather than simply replacing it? Maybe this will work for you:

globals [ genome ]

to setup
  ca
  set genome n-values 5 [ random 101 / 100 ]
  print word "Original genome: " genome
  reset-ticks
end

to mutate
  set genome map [ 
    i -> 
    ifelse-value ( random-float 1 < 0.2 )
    [ precision ( i + one-of [ 0.01 -0.01 ] ) 2 ]
    [ i ]
  ] genome
  print word "Mutated genome:  " genome
end

Here, the genome is randomly created in setup, and then every time you call mutate, each gene has a chance of being either increased or decreased by 0.01. Output:

Original genome: [0.09 0.77 0.41 0.97 0.8]
Mutated genome:  [0.08 0.77 0.41 0.96 0.8]
Mutated genome:  [0.08 0.76 0.41 0.97 0.8]
Mutated genome:  [0.08 0.75 0.41 0.97 0.8]
Mutated genome:  [0.09 0.75 0.42 0.97 0.8]