palette {grDevices}

Set or View the Graphics Palette

Description

View or manipulate the color palette which is used when col= has a numeric index and supporting functions.

Usage

palette(value)
palette.pals()
palette.colors(n = NULL, palette = "Okabe-Ito", alpha, recycle = FALSE,
               names = FALSE)

Arguments

value

an optional character vector specifying a new palette (see Details).

n

the number of colors to select from a palette. The default NULL selects all colors of the given palette.

palette

a valid palette name (one of palette.pals()). The name is matched to the list of available palettes, ignoring upper vs. lower case, spaces, dashes, etc. in the matching.

alpha

an alpha-transparency level in the range [0,1] (0 means transparent and 1 means opaque).

recycle

logical indicating what happens in case n > length(palette(.)). By default (recycle = FALSE), the result is as for n = NULL, but with a warning.

names

logical indicating whether a named vector of colors should be returned or not (provided that the palette has any names for its colors).

Details

The palette() function gets or sets the current palette, the palette.pals() function lists the available predefined palettes, and the palette.colors() function selects colors from the predefined palettes.

The color palette and referring to colors by number (see e.g. par) was provided for compatibility with S. R extends and improves on the available set of palettes.

If value has length 1, it is taken to be the name of a built-in color palette. The available palette names are returned by palette.pals(). It is also possible to specify "default".

If value has length greater than 1 it is assumed to contain a description of the colors which are to make up the new palette. The maximum size for a palette is 1024 entries.

If value is omitted, no change is made to the current palette.

There is only one palette setting for all devices in an R session. If the palette is changed, the new palette applies to all subsequent plotting.

The current palette also applies to re-plotting (for example if an on-screen device is resized or dev.copy or replayPlot is used). The palette is recorded on the display list at the start of each page and when it is changed.

Value

palette() returns a character vector giving the colors from the palette which was in effect. This is invisible unless the argument is omitted.

palette.pals() returns a character vector giving the names of predefined palettes.

palette.colors() returns a vector of R colors. By default (if names = FALSE the vector has no names. If names = TRUE, the function attempts to return a named vector if possible, i.e., for those palettes that provide names for their colors (e.g., "Okabe-Ito", "Tableau 10", or "Alphabet").

See Also

colors for the vector of built-in named colors; hsv, gray, hcl.colors, ... to construct colors.

adjustcolor, e.g., for tweaking existing palettes; colorRamp to interpolate colors, making custom palettes; col2rgb for translating colors to RGB 3-vectors.

Examples

require(graphics)

palette()               # obtain the current palette
palette("R3");palette() # old default palette
palette("ggplot2")      # ggplot2-style palette
palette()

palette(hcl.colors(8, "viridis"))

(palette(gray(seq(0,.9,length.out = 25)))) # gray scales; print old palette
matplot(outer(1:100, 1:30), type = "l", lty = 1,lwd = 2, col = 1:30,
        main = "Gray Scales Palette",
        sub = "palette(gray(seq(0, .9, len=25)))")
palette("default")      # reset back to the default

## on a device where alpha transparency is supported,
##  use 'alpha = 0.3' transparency with the default palette :
mycols <- adjustcolor(palette(), alpha.f = 0.3)
opal <- palette(mycols)
x <- rnorm(1000); xy <- cbind(x, 3*x + rnorm(1000))
plot (xy, lwd = 2,
       main = "Alpha-Transparency Palette\n alpha = 0.3")
xy[,1] <- -xy[,1]
points(xy, col = 8, pch = 16, cex = 1.5)
palette("default")

## List available built-in palettes
palette.pals()

## Demonstrate the colors 1:8 in different palettes using a custom matplot()
sinplot <- function(main=NULL, n = 8) {
    x <- outer(
	seq(-pi, pi, length.out = 50),
	seq(  0, pi, length.out = n),
	function(x, y) sin(x - y)
    )
    matplot(x, type = "l", lwd = 4, lty = 1, col = 1:n, ylab = "", main=main)
}
sinplot("default palette")

palette("R3");        sinplot("R3")
palette("Okabe-Ito"); sinplot("Okabe-Ito")
palette("Tableau")  ; sinplot("Tableau", n = 10)
palROB <- colorRampPalette(c("red", "darkorange2", "blue"), space = "Lab")
palette(palROB(16)); sinplot("palROB(16)", n = 16)
palette("default") # reset

## color swatches for palette.colors()
palette.swatch <- function(palette = palette.pals(), n = 8, nrow = 8,
                           border = "black", cex = 1, ...)
{
     cols <- sapply(palette, palette.colors, n = n, recycle = TRUE)
     ncol <- ncol(cols)
     nswatch <- min(ncol, nrow)
     op <- par(mar = rep(0.1, 4),
               mfrow = c(1, min(5, ceiling(ncol/nrow))),
     	       cex = cex, ...)
     on.exit(par(op))
     while (length(palette)) {
 	subset <- seq_len(min(nrow, ncol(cols)))
 	plot.new()
 	plot.window(c(0, n), c(0.25, nrow + 0.25))
 	y <- rev(subset)
 	text(0, y + 0.1, palette[subset], adj = c(0, 0))
 	y <- rep(y, each = n)
 	rect(rep(0:(n-1), n), y, rep(1:n, n), y - 0.5,
 	     col = cols[, subset], border = border)
 	palette <- palette[-subset]
 	cols    <- cols [, -subset, drop = FALSE]
     }
}

palette.swatch()

palette.swatch(n = 26) # show full "Alphabet"; recycle most others