rainbow(n, s=1, v=1, start=0, end=(n-1)/n,
xdelta=0.07, ydelta=0.014)
n
| the number of colors in the rainbow. |
s,v
| the ``saturation'' and ``value'' to be used to complete the HSV color descriptions. |
start
| the (corrected) hue at which the rainbow begins. |
end
| the (corrected) hue at which the rainbow ends. |
xdelta
| the first correction factor. |
ydelta
| the second correction factor. |
n colors.
Equispaced hues in RGB space tend to cluster at
the red, green and blue primaries.
This function applies an ad-hoc correction to
diminish the effect of this clustering, producing
``visually equispaced'' colors.
The correction applied by rainbow was derived
for a particular SVGA display and may not look right
on other displays.
Some applications such as contouring require a pallette
of colors which do not ``wrap around'' to give a final
color close to the starting one.
The parameters start and end can be used
to specify particular subranges of hues.
The following values can be used when generating
such a subrange:
red=0, yellow=1/6, green=2/6, cyan=3/6, blue=4/6 and magenta=5/6.
The values returned by rainbow can be used with a
col= specification in graphics functions or in par.
See Also
rgb, hsv, gray.
Examples
# A Color Wheel
piechart(rep(1,12),col=rainbow(12))