A simple interface to select colours

colour-picker.R

colour_picker <- function() {
    n <- length(colours())
    i <- ceiling(sqrt(n))
    m <- matrix(c(1:n, rep(NA, i^2 - n)),
                ncol = i, nrow = i)
    ## plotting
    image(m, col = colours(),
          xaxt = "n", yaxt = "n")
    k <- seq(0, 1, length.out = i)
    kk <- expand.grid(k, k)
    kk <- kk[1:n, ]
    ## points(kk)
    ## choosing
    identifycol <- function(x, y = NULL, n = length(x), pch = 19) {
        ## from ?identify
        k <- 1
        xy <- xy.coords(x, y); x <- xy$x; y <- xy$y
        sel <- rep(FALSE, length(x)); res <- integer(0)
        while(sum(sel) < n) {
            ans <- identify(x[!sel], y[!sel], n = 1, plot = FALSE)
            if (!length(ans)) break
            ans <- which(!sel)[ans]
            text(x[ans], y[ans], k, cex = 1.5)
            k <- k + 1
            sel[ans] <- TRUE
            res <- c(res, ans)
        }
        res
    }
    ans <- identifycol(kk)
    ans <- scales::col2hcl(colours()[ans])
    return(ans)
}

Do you mind making a few tiny edits so that I don't have to fork it into my own gist? The above didn't work for me out of the box, had to make these small adjustments:

• replace i <- 26 with i <- ceiling(sqrt(n))
• replace rep(NA, m) with rep(NA, i^2 - n) (m is not defined)
• change the call to col2hcl to scales::col2hcl (or add a library(scales))

Sorry, I missed you comments. Thank you very much for your suggestions!