Generate Uniform Clusters and Plot with ggplot2

gistfile1.txt

library('plyr')
library('reshape2')
library('ggplot2')

bivar_unif <- function(n, a1, b1, a2, b2) {
  cbind(runif(n, a1, b1), runif(n, a2, b2))
}

gen_unif <- function(n = 25, delta = 0, seed = NULL) {
  if(is.null(seed)) {
    seed <- delta
  }
  set.seed(seed)
  
  pop1 <- c(-1/2, 1/2, delta - 1/2, delta + 1/2)
  pop2 <- c(delta - 1/2, delta + 1/2, -1/2, 1/2)
  pop3 <- c(-1/2, 1/2, -delta - 1/2, -delta + 1/2)
  pop4 <- c(-delta - 1/2, -delta + 1/2, -1/2, 1/2)
  
  unif_pops <- rbind.data.frame(pop1, pop2, pop3, pop4)
  colnames(unif_pops) <- c("a1", "b1", "a2", "b2")
  unif_pops$n <- n
  
  x <- mdply(unif_pops, as.data.frame(bivar_unif), .expand = F)
  colnames(x) <- c("Population", "x1", "x2")
  x$Population <- as.factor(x$Population)  
  x
}

x <- gen_unif(25, 2)
p <- ggplot(x, aes(x = x1, y = x2, group = Population))
p + geom_point(aes(color = Population))