colorRampPalette {geneplotter}R Documentation

Extend a color palette to a color ramp

Description

These functions are useful for converting hand-designed `sequential' or `diverging' color schemes into continous color ramps eg for image and filled contour plots.

Usage

colorRampPalette(palette, bias = 1,method=c("linear","spline"))
colorRamp(palette, bias=1,method=c("spline","linear"))

Arguments

palette A vector of colors
bias Bias >1 puts more colors at high values, <1 puts more at low values
method Interpolation method. Spline interpolation may give smoother results but can end up outside the valid RGB space, especially with highly saturated palettes or those based on a small starting set.

Value

colorRampPalette returns a palette generating function like terrain.colors or heat.colors that takes an integer argument and generates a palette with that many colors.
colorRamp returns a color generating function, that takes a number between 0 and 1 and generates the corresponding color.

Author(s)

Thomas Lumley

See Also

www.colorbrewer.org

Examples

   m<-outer(1:20,1:20,function(x,y) sin(sqrt(x*y)/3))

   redblue<-colorRampPalette(c("red","orange","blue"))
   filled.contour(m,color.palette=redblue)

   yb<-colorRampPalette(c("yellow2","goldenrod","darkred"))
   filled.contour(m,color.palette=yb)

   yb<-colorRampPalette(c("yellow2","goldenrod","darkred"),bias=0.5)
   filled.contour(m,color.palette=yb)

   ## Two ColorBrewer sequential palettes
   ylOrBn4<-c("#FFFFD4", "#FED98E", "#FE9929","#CC4C02")
   ylGnBl5<-c("#FFFFCC","#C7E9B4","#7FCDBB","#40B6C4","#2C7FB8" ,"#253494")

   ylOrBn<-colorRampPalette(ylOrBn4)
   ylGnBl<-colorRampPalette(ylGnBl5,method="spline")
   filled.contour(m,color.palette=ylOrBn)
   filled.contour(m,color.palette=ylGnBl)

   if(require("RColorBrewer")){
        RdBu7<-colorRampPalette(brewer.pal(7,"RdBu"),method="spline")
        RWB<-colorRampPalette(c("red","white","blue"))
        redblue<-colorRampPalette(c("red","blue"))
        filled.contour(m,color.palette=redblue,main="naive red-blue")
        filled.contour(m,color.palette=RWB,main="naive red-white-blue")
        filled.contour(m,color.palette=RdBu7,main="ColorBrewer RdBu7")
   }


[Package geneplotter version 1.4.0 Index]