colorPalette: Color interpolation with uneven step size

In marchtaylor/sinkr: Collection of functions with emphasis in multivariate data analysis

Color interpolation with uneven step size

Description

Color ramp with differing number of steps between color levels. Wrapper for colorRamp.

Usage

colorPalette(steps, n.steps.between = NULL, ...)

Arguments

steps	colors to interpolate; must be a valid argument to col2rgb().
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 colorRamp.

Details

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..

Examples

# 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)

marchtaylor/sinkr documentation built on July 4, 2022, 5:48 p.m.