Color choosing in R made easy
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I don’t know about you, but when I want to make a graph in R, I handpick the colors, line widths etc… to produce awesome output.
A lot of my time is spent on color choosing, I had to find a more convenient way of doing so. Earl F. Glynn’s “Chart of R colors” posted on http://research.stowers-institute.org/efg/R/Color/Chart/ gave me the idea to the following function.
R has an Internal called colors(), it’s output is a 657 long character vector of reserved names for colors.
The names can be used directly as in :
plot(iris,col="orange")
Alternatively, they can be referred to from colors()
plot(iris,col=colors()[503])
The color() function has a two arguments (notice it is not plural… I chose this unreserved name because it’s easy to remember) :
- plot.it – FALSE by default
- locate – 0 by default
The call color() is the same as colors().
> color()[555]==colors()[555] [1] TRUE
Calling color(plot.it=T) or color(T) gives the following output (very similar to Earl F. Glynn’s “Chart of R colors”) :
You can choose and remember the numbers, or print and stick above your working area… but the following makes color() more useful :
Specifying locate = k > 0 will plot the chart above and this time will use the locator() function in a loop to choose colors you want. After choosing k colors the output will be a k-long character vector of the chosen colors.
> color(T,5) [1] "firebrick4" "grey9" "green" "gray99" "khaki1"
You can use it directly in a plot function, the palette of colors will plot first, choose your colors, the plot you called for will be followed by it:
plot(iris,col=color(T,5))
The function is given by :
color <- function (plot.it=F,locate=0) { if(!plot.it) { return(.Internal(colors())) # so far, not different from colors() } # close on if else { ytop <- rep(seq(1/26,1,by=1/26),each=26)[1:657] ybottom <- rep(seq(0,1-1/26,by=1/26),each=26)[1:657] xleft <- rep(seq(0,1-1/26,by=1/26),times=26)[1:657] xright <- rep(seq(1/26,1,by=1/26),times=26)[1:657] pall <- round(col2rgb(colors())/256) pall <- colSums(pall) ; pall2 <- character(0) pall2[pall>0] <- "black" pall2[pall==0] <- "white" par(mar=c(0,0,1,0)) plot.new() title(main="Palette of colors()") rect(xleft,ybottom,xright,ytop,col=colors()) text(x=xleft+((1/26)/2) ,y=ytop-((1/26)/2) ,labels = 1:657 ,cex=0.55 ,col=pall2) } # close on else if(locate==0) print("Palette of colors()") else { colmat <- matrix(c(1:657,rep(NA,26^2-657)),byrow=T,ncol=26,nrow=26) cols <- NA i <- NA for(i in 1:locate) { h <- locator(1) if(any(h$x<0,h$y<0,h$x>1,h$y>1)) stop("locator out of bounds!") else { cc <- floor(h$x/(1/26))+1 rr <- floor(h$y/(1/26))+1 cols[i] <- .Internal(colors())[colmat[rr,cc]] } # close on else } # close on i return(cols) } # close on else } # close on else+function
You can also write it to variable for further use:
> cols<- color(T,5) > cols [1] "magenta" "orange3" "palevioletred2" "seagreen4" [5] "seagreen2"
Of course it’s not perfect, I still have not solved issues of working with Devices such as pdf() jpeg() and such…
Your comments are welcome.
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