setwd("~")

pkgs <- c("stringr", "plyr", "dplyr", "reshape2",
          "parallel", "snow", "ggplot2")
sapply(pkgs, library, character.only = TRUE, quietly = TRUE)

used_cores <- detectCores(logical = FALSE)
cluster <- makePSOCKcluster(used_cores)
clusterExport(cluster, "pkgs")
clusterEvalQ(cluster, sapply(pkgs, require, character.only = TRUE))

eg <- function(nm) {
  x <- rnorm(100)
  df <- ldply(c(0.1, 0.5, 1), function(bw) {
    data.frame(bw,
               getAnywhere(bin)[which(getAnywhere(bin)$where ==
                                        "namespace:ggplot2")](x, binwidth = bw))
  })
  tryCatch({tmp <- ggplot(df) +
    geom_histogram(aes(x, y = density, width = width), stat = "identity") +
    facet_wrap(~bw)
  ggsave(paste0(nm, ".png"), tmp)
  })
}

parLapplyLB(cluster, 1:10000, eg)