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 255, they
are rescaled to that range regardless of the value of scale.up.
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.
vectors of the values of the color components
either as 0 to 1 or ,if any value is greater than 1, 0 to 255.
nslices
The number of color "slices".
scale.up
Whether to scale color values less than or equal to 1 into a
0->255 range. If colors are specified in a 0->1 range, set this to TRUE or
all colors will be essentially black.
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),scale.up=TRUE)