Hi, Before calling the second ga, I am just altering the columns of dat except the first column
Dat = Dat[, c(1, 1 + sample(1:30, 30, replace = F))] With that, I expect the positions of the elements of x will be changed, but objective function should return the same value, same for ga. Below is an illustration. Altered_Pos = 1 + sample(1:30, 30, replace = F) x = rnorm(30) Fitness_Fn(x) ### -0.0004543259 Dat = Dat[, c(1, Altered_Pos)] Fitness_Fn(x[Altered_Pos - 1]) ### -0.0004543259 On Wed, 7 May 2025 at 21:32, Michael Dewey <li...@dewey.myzen.co.uk> wrote: > Dear Daniel > > As far as I can see you have re-generated the data before calling ga() > so the data is not just a permutation of the first set. > > Michael > > On 07/05/2025 15:36, Daniel Lobo wrote: > > I am using *Genetic Algorithm* to maximize some function which use data. > > > > I use GA package in R for this ( > > https://cran.r-project.org/web/packages/GA/index.html) > > > > Below is my code > > > > library(GA) > > set.seed(1) > > Dat = data.frame(rnorm(1000), matrix(rnorm(1000 * 30), nc = 30)) > > > > Fitness_Fn = function(x) { > > return(cor(Dat[, 1], as.matrix(Dat[, -1]) %*% matrix(x, nc = > 1))[1,1]) > > } > > > > ga(type = 'real-valued', fitness = Fitness_Fn, seed = 1, lower = > > rep(0, 30), upper = rep(1, 30), elitism = 10, popSize = 200, maxiter = > > 1, pcrossover = 0.9, pmutation = 0.9, run = 1) > > > > However now I alter the columns of my data and rerun the GA > > > > Dat = Dat[, c(1, 1 + sample(1:30, 30, replace = F))] > > Fitness_Fn = function(x) { > > return(cor(Dat[, 1], as.matrix(Dat[, -1]) %*% matrix(x, nc = > 1))[1,1]) > > } > > > > ga(type = 'real-valued', fitness = Fitness_Fn, seed = 1, lower = > > rep(0, 30), upper = rep(1, 30), elitism = 10, popSize = 200, maxiter = > > 1, pcrossover = 0.9, pmutation = 0.9, run = 1) > > > > Surprisingly, I get different result from above 2 implementations. > > > > In first case, I get > > > > GA | iter = 1 | Mean = 0.01534124 | Best = 0.04351926 > > > > In second case, > > > > GA | iter = 1 | Mean = 0.01705027 | Best = 0.04454167 > > > > I have fixed the random number generation using seed = 1 in the ga() > function, > > So I am expecting I would get exactly same result. > > > > Could you please help identify the issue here? I want to get exactly same > > result irrespective of the order of the columns of dat for above > function. > > > > Thanks for your time. > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > https://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > -- > Michael Dewey > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
