From Andreas.Weingessel@ci.tuwien.ac.at  Fri Mar 13 11:22:40 1998
From: Andreas.Weingessel@ci.tuwien.ac.at (Andreas Weingessel)
Date: Fri, 13 Mar 1998 12:22:40 +0100
Subject: heat.colors
Message-ID: <199803131122.MAA09519@elendil.ci.tuwien.ac.at>


Currently, heat.colors gives the following code:

R> heat.colors(4)
[1] "#FF0000" "#FF7F00" "#FFFF00" "#FFFF7F"
R> heat.colors(5)
[1] "#FF0000" "#FF5400" "#FFA900" "#FFFF00" "#FFFF7F"
R> heat.colors(6)
[1] "#FF0000" "#FF3F00" "#FF7F00" "#FFBF00" "#FFFF00" "#FFFF7F"
R> heat.colors(7)
[1] "#FF0000" "#FF3300" "#FF6600" "#FF9900" "#FFCC00" "#FFFF00" "#FFFF7F"

That means, the distance between the last color and the last color but
one stays the same (7F), whereas the distances between other adjacent
colors drops with the number of coloros from 7F to 33.

The code for heat.colors(n) looks like
                j <- n%/%4
                i <- n - j
                c(rainbow(i, start = 0, end = 1/6), if (j > 0) hsv(h = 1/6, 
                        s = seq(from = 1 - 1/(2 * j), to = 1/(2 * 
                                j), length = j), v = 1))


If for example, n=16, j=4, i=12. That is, for the first 12 colors the
interval "#FF0000" to "#FFFF00" is divided into 12 pieces, for the
last 4 colors an interval of the same length "#FFFF00" to "#FFFFFF" is
only divided into 4 pieces.

Does this really provide n ``contiguous'' colors or are the first 12
colors closer together than the last 4?

	Andreas
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heat.colors
Andreas Weingessel