Hi Luca,
I do not know how to do this in python, but I know how to do it with R.
Since R is GNU/GPL, you can probably take some code from it or use the
same algorithms. Have a look here for some examples:
http://www.r-bloggers.com/color-palettes-in-r/
This R blogger also give a link:
http://research.stowers-institute.org/efg/Report/UsingColorInR.pdf
which is useful even if you do not care about R (see p. 21 sqq on color
models, including Hue-Saturation-Value model, and the references at the
end).
If you are new to R, just type a function name without parenthesis and
type enter. Example session:
topo.colors
function (n, alpha = 1)
{
if ((n - as.integer(n[1L])) 0) {
j - n%/%3
k - n%/%3
i - n - j - k
c(if (i 0) hsv(h = seq.int(from = 43/60, to = 31/60,
length.out = i), alpha = alpha), if (j 0) hsv(h =
seq.int(from = 23/60,
to = 11/60, length.out = j), alpha = alpha), if (k
0) hsv(h = seq.int(from = 10/60, to = 6/60, length.out =
k),
alpha = alpha, s = seq.int(from = 1, to = 0.3, length.out =
k),
v = 1))
}
else character(0L)
}
Hope it helps
Mayeul
Le mercredi 10 novembre 2010 à 00:00 +0100, Luca Delucchi a écrit :
Hi everybody, I'm working on OGR2Layers python plugin, I'd like to
implement also continuous color style, but I didn't understand how can
I assign a style to each features. With also style type like unique
value or graduated I had all the classes of style (symbols class) with
continuous color I had only the first (min value) and the last (max
value), is there some mathematical functions for calculate the
intermediate classes?
Thank's
Luca
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