[I neglected to check some details in the previous post]
This one should work better,
library(grid)
x= c(0, 0.5, 1)
y= c(0.5, 1, 0.5)
grid.polygon(x=x, y=y, gp=gpar(fill=NA, col="grey90")) # outer shell
xx <- seq(range(x)[1],range(x)[2], length=100)
dx <- diff(xx) # width of clipped triangles
cols <- colorRampPalette(c("green", "lightgray"))(length(dx))
for(ii in seq_along(xx[-length(xx)])){
grid.clip(x=xx[ii], y=0.5,
width= 1.2*dx[ii], # fudge factor to overlap well
height=1,
just="bottom")
# if(ii%%2)# testing with every other masked
grid.polygon(x=c(0, 0.5, 1), y=c(0.5, 1, 0.5), gp=gpar(fill=cols[ii],
col=cols[ii]))
}
HTH,
baptiste
Kexin Ji wrote:
Hi,
I wonder whether there is a way to generate a polygon (a triangle in
my case) with color gradient using grid.polygon() in package grid?
I tried something like
library(grid)
grid.polygon(x=c(0, 0.5, 1), y=c(0.5, 1, 0.5), gp=gpar(col=NA,
fill=colorRampPalette(c("green", "lightgray"),
space="Lab")(200)))
But am only getting a triangle filled with color green, whereas the
aim is a triangle of color gradient from green to lightgray.
Can grid.polygon() generate a color gradient, or am I being mistaken?
Best to my knowledge, is it true that R currently doesn't contain any
other function that might generate a polygon with color gradient?
Thank you!
Kexin
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_____________________________
Baptiste Auguié
School of Physics
University of Exeter
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Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
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