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library(ggplot2)
library(gganimate)
library(grDevices)
rand.pupulation <- function(n) {
return(matrix(runif(2*n), ncol=2))
}
alpha.fixed <- function(alpha) {
return(function() alpha)
}
alpha.runif <- function() {
return(function() runif(1))
}
recom.singlearithm <- function(alpha_gen) {
return(function(parents) {
alpha <- alpha_gen()
gene_index <- sample(1:ncol(parents), 1)
gene_p1 <- parents[1, gene_index]
gene_p2 <- parents[2, gene_index]
children <- parents
children[1,gene_index] <- alpha * gene_p2 + (1 - alpha) * gene_p1
children[2,gene_index] <- alpha * gene_p1 + (1 - alpha) * gene_p2
return(children)
})
}
recom.wholearithm <- function(alpha_gen) {
return(function(parents) {
alpha <- alpha_gen()
children <- parents
children[1,] <- alpha * children[1,] + (1 - alpha) * children[2,]
children[2,] <- alpha * children[2,] + (1 - alpha) * children[1,]
return(children)
})
}
next.population <- function(population, recom) {
next_population <- matrix(, nrow=0, ncol=2)
parent_pairs <- matrix(sample(1:nrow(population), nrow(population)), ncol=2)
for(i in 1:nrow(parent_pairs)) {
parents <- parent_pairs[i,]
next_population <- rbind(next_population, recom(population[parents,]))
}
return(next_population)
}
experiment <- function(population, gen, recom) {
df <- data.frame( x = population[,1]
,y = population[,2]
,generation = 0)
for(g in 1:gen) {
population <- next.population(population, recom)
df <- rbind(df, data.frame( x = population[,1]
,y = population[,2]
,generation = g))
}
return(df)
}
plot.experiment <- function(df, filename) {
pdf(file=filename, onefile=TRUE)
for(g in unique(df$generation)) {
tmp_df <- df[df$generation == g,]
p <- ggplot(data=tmp_df, aes(x=x, y=y)) +
geom_point() +
labs(title=sprintf("generation: %d", g)) +
xlim(0, 1) +
ylim(0, 1)
hull <- chull(tmp_df$x, tmp_df$y)
p <- p + geom_polygon(data=tmp_df[hull,], alpha=0.25)
print(p)
}
dev.off()
}
all.experiments <- function() {
population <- rand.pupulation(20)
df <- experiment(population, 10, recom.singlearithm(alpha.fixed(0.5)))
plot.experiment(df, "single_fixed_alpha.pdf")
df <- experiment(population, 10, recom.singlearithm(alpha.runif()))
plot.experiment(df, "single_rand_alpha.pdf")
df <- experiment(population, 10, recom.wholearithm(alpha.fixed(0.5)))
plot.experiment(df, "whole_fixed_alpha.pdf")
df <- experiment(population, 10, recom.wholearithm(alpha.runif()))
plot.experiment(df, "whole_rand_alpha.pdf")
}