color.gradient: Calculate an arbitrary sequence of colors.
Description
color.gradient calculates sequences of colors by linearly
interpolating between the values specified for each color. If the length
of a vector of colors is the same as nslices it is not changed.
If any length is greater than nslices, it is truncated to that
length. If any color values are less than 0 or greater than 1, they
are rescaled to that range.
The function is mainly useful for defining a set of colors to represent
a known number of gradations. Such a set can be used to assign a grade
to values (e.g. points on a scatterplot) and display a color bar using
gradient.rect as a legend.
Usage
color.gradient(reds,greens,blues,nslices=50)
Arguments
reds,greens,blues
vectors of the values of the color components
as 0 to 1.
nslices
The number of color "slices".
Value
A vector of hexadecimal color values as used by col.
# try it with red endpoints, green midpoints, and a blue vector longer# than 'nslices' color.gradient(c(0,1),c(1,0.6,0.4,0.3,0),seq(0.1,0.6,length=60))