The funny functions in R

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demo('colors')

    demo(colors)
    ---- ~~~~~~

> ### ----------- Show (almost) all named colors ---------------------
> 
> ## 1) with traditional 'graphics' package:
> showCols1 <- function(bg = "gray", cex = 0.75, srt = 30) {
+     m <- ceiling(sqrt(n <- length(cl <- colors())))
+     length(cl) <- m*m; cm <- matrix(cl, m)
+     ##
+     require("graphics")
+     op <- par(mar=rep(0,4), ann=FALSE, bg = bg); on.exit(par(op))
+     plot(1:m,1:m, type="n", axes=FALSE)
+     text(col(cm), rev(row(cm)), cm,  col = cl, cex=cex, srt=srt)
+ }

> showCols1()

> ## 2) with 'grid' package:
> showCols2 <- function(bg = "grey", cex = 0.75, rot = 30) {
+     m <- ceiling(sqrt(n <- length(cl <- colors())))
+     length(cl) <- m*m; cm <- matrix(cl, m)
+     ##
+     require("grid")
+     grid.newpage(); vp <- viewport(w = .92, h = .92)
+     grid.rect(gp=gpar(fill=bg))
+     grid.text(cm, x = col(cm)/m, y = rev(row(cm))/m, rot = rot,
+               vp=vp, gp=gpar(cex = cex, col = cm))
+ }

> showCols2()

> showCols2(bg = "gray33")

> ###
> 
> ##' @title Comparing Colors
> ##' @param col
> ##' @param nrow
> ##' @param ncol
> ##' @param txt.col
> ##' @return the grid layout, invisibly
> ##' @author Marius Hofert, originally
> plotCol <- function(col, nrow=1, ncol=ceiling(length(col) / nrow),
+                     txt.col="black") {
+     stopifnot(nrow >= 1, ncol >= 1)
+     if(length(col) > nrow*ncol)
+         warning("some colors will not be shown")
+     require(grid)
+     grid.newpage()
+     gl <- grid.layout(nrow, ncol)
+     pushViewport(viewport(layout=gl))
+     ic <- 1
+     for(i in 1:nrow) {
+         for(j in 1:ncol) {
+             pushViewport(viewport(layout.pos.row=i, layout.pos.col=j))
+             grid.rect(gp= gpar(fill=col[ic]))
+             grid.text(col[ic], gp=gpar(col=txt.col))
+             upViewport()
+             ic <- ic+1
+         }
+     }
+     upViewport()
+     invisible(gl)
+ }

> ## A Chocolate Bar of colors:
> plotCol(c("#CC8C3C", paste0("chocolate", 2:4),
+           paste0("darkorange", c("",1:2)), paste0("darkgoldenrod", 1:2),
+           "orange", "orange1", "sandybrown", "tan1", "tan2"),
+         nrow=2)

> ##' Find close R colors() to a given color {original by Marius Hofert)
> ##' using Euclidean norm in (HSV / RGB / ...) color space
> nearRcolor <- function(rgb, cSpace = c("hsv", "rgb255", "Luv", "Lab"),
+                        dist = switch(cSpace, "hsv" = 0.10, "rgb255" = 30,
+                        "Luv" = 15, "Lab" = 12))
+ {
+     if(is.character(rgb)) rgb <- col2rgb(rgb)
+     stopifnot(length(rgb <- as.vector(rgb)) == 3)
+     Rcol <- col2rgb(.cc <- colors())
+     uniqC <- !duplicated(t(Rcol)) # gray9 == grey9 (etc)
+     Rcol <- Rcol[, uniqC] ; .cc <- .cc[uniqC]
+     cSpace <- match.arg(cSpace)
+     convRGB2 <- function(Rgb, to)
+         t(convertColor(t(Rgb), from="sRGB", to=to, scale.in=255))
+     ## the transformation,  rgb{0..255} --> cSpace :
+     TransF <- switch(cSpace,
+                      "rgb255" = identity,
+                      "hsv" = rgb2hsv,
+                      "Luv" = function(RGB) convRGB2(RGB, "Luv"),
+                      "Lab" = function(RGB) convRGB2(RGB, "Lab"))
+     d <- sqrt(colSums((TransF(Rcol) - as.vector(TransF(rgb)))^2))
+     iS <- sort.list(d[near <- d <= dist])# sorted: closest first
+     setNames(.cc[near][iS], format(d[near][iS], digits=3))
+ }

> nearRcolor(col2rgb("tan2"), "rgb")
         0.0         21.1         25.8         29.5 
      "tan2"       "tan1" "sandybrown"    "sienna1" 

> nearRcolor(col2rgb("tan2"), "hsv")
      0.0000       0.0410       0.0618       0.0638       0.0667       0.0766       0.0778       0.0900       0.0912 
      "tan2"    "sienna2"     "coral2"    "tomato2"       "tan1"      "coral"    "sienna1" "sandybrown"     "coral1" 
      0.0918 
    "tomato" 

> nearRcolor(col2rgb("tan2"), "Luv")
        0.00         7.42         7.48        12.41        13.69 
      "tan2"       "tan1" "sandybrown"    "orange3"    "orange2" 

> nearRcolor(col2rgb("tan2"), "Lab")
        0.00         5.56         8.08        11.31 
      "tan2"       "tan1" "sandybrown"       "peru" 

> nearRcolor("#334455")
         0.0867 
"darkslategray" 

> ## Now, consider choosing a color by looking in the
> ## neighborhood of one you know :
> 
> plotCol(nearRcolor("deepskyblue", "rgb", dist=50))

> plotCol(nearRcolor("deepskyblue", dist=.1))

> plotCol(nearRcolor("tomato", "rgb", dist= 50), nrow=3)

> plotCol(nearRcolor("tomato", "hsv", dist=.12), nrow=3)

> plotCol(nearRcolor("tomato", "Luv", dist= 25), nrow=3)

> plotCol(nearRcolor("tomato", "Lab", dist= 18), nrow=3)

pie(rep(1,19),col=rainbow(19),main='rainbow19')

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