R/casthex.R

In jacobgolan/HEXeR: Extract HEX color codes from image URLs

#' Extract HEX codes from image url
#'
#' List as many URLs to image files as you want
#'
#' @param infile Path to the input urls
#' @return hex codes
#' @export
casthex<-function(x){
  unique(unlist(
    lapply(x,
           function(urls){
             download.file(urls,"temp.png",mode="wb")
             img <- load.image('temp.png')

             getHexPrimaries <- function(img, pcnt.threshold = 0.05){
               #convert cimg to workable format
               channel.labels <- c('R','G','B','A')[1:dim(img)[4]]
               img <- as.data.table(as.data.frame(img))
               img[,channel := factor(cc ,labels=channel.labels)]
               img <- dcast(img, x+y ~ channel, value.var = "value")
               #sort by unique rgb combinations and identify the primary colours
               colours.sorted <- img[, .N, by=list(R,G,B)][order(-N)]
               colours.sorted[ , primary := N/sum(N) > pcnt.threshold]
               #convert to hex
               hex.primaries <-
                 apply(colours.sorted[primary==TRUE], 1, function(row){
                   hex <- rgb(row[1], row[2], row[3], maxColorValue=1)
                   hex
                 })
               hex.primaries
             }


             getHexPrimaries(img)}
    )  ))

}