colorPalette | R Documentation |
Color ramp with differing number of steps between color levels. Wrapper for
colorRamp
.
colorPalette(steps, n.steps.between = NULL, ...)
steps |
colors to interpolate; must be a valid argument to |
n.steps.between |
number of color steps in between each color. Allows one to strech out specified colors more than others. Defaust is that all steps have the same weighting. |
... |
arguments to pass to |
This is a wrapper function for colorRampPalette. It allows for the definition of the number of intermediate colors between the main colors. Using this option one can stretch out colors that should predominate the palette spectrum. Additional arguments of colorRampPalette can also be added regarding the type and bias of the subsequent interpolation..
# Color scales with and without steps in between op <- par(mfcol=c(2,1), omi=c(0.1,0.1,0.1,0.1), mai=c(1,0.2,0.2,0.2)) steps <- c("blue4", "cyan", "white", "yellow", "red4") pal <- colorPalette(steps, space="rgb") z=1:1000 imageScale(z, col=pal(41)) box() steps <- c("blue4", "cyan", "white", "yellow", "red4") pal <- colorPalette(steps, c(20,1,1,20), space="rgb") z=1:1000 imageScale(z, col=pal(41)) box() par(op) # Use of transparency in palette (via alpha=TRUE) op <- par(mar=c(2,2,2,2)) snow <- replace(volcano, volcano<150, NaN) * 1e-8*volcano^3 elevation.pal <- colorPalette(c("black", "blue", "red"), c(1,6)) snow.pal <- colorPalette(c(rgb(0.9,0.9,0.9,0), rgb(0.9,0.9,0.9,1)), alpha=TRUE) image(volcano, col=elevation.pal(100), axes=FALSE) image(snow, col=snow.pal(100), add=TRUE) contour(volcano, add=TRUE, levels=150, col="white", lwd=2, cex=2) text(0.3, 0.9, "Snow line", col="white") par(op)
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