CODEWITHSUNDEEP
algorithmgenetic-algorithmgenetic-programmingmutation
YevgenyL
YevgenyL

Reputation: 321

Mutation step-size in genetic algorithm

Can someone explain to me what means "mutation step size" ? I'm reading an article regarding genetic algorithms and it says:

"the mutation randomly changes the decision of a node or mutate the value with a step-size of 0.25"

I know the role of mutation in GA life cycle , but I can't find a good explanation for what is step size of mutation.

thanks.

Upvotes: 2

Views: 1984

Answers (1)

chubbsondubs
chubbsondubs

Reputation: 38676

Essentially it's how far a mutation can be away from the last value.

"As far as real-valued search spaces are concerned, mutation is normally performed by adding a normally distributed random value to each vector component. The step size or mutation strength (i.e. the standard deviation of the normal distribution) is often governed by self-adaptation (see evolution window)."

That's complex talk for given a vector you are mutating (say X = [x1,x2,..,xN]) then you'll modify that vector's values by some random amount that won't be more than the mutation step size. So say we had a function called normal(v,stdDev) that generated random values with a normal distribution around some value with stdDev. Then we'd modify each value of that vector with the following psuedo code:

for x in X {
   x = normal(x,mutationStepSize)
}

Upvotes: 2

Related Questions