On May 7, 2012, at 6:15 PM, stat curio wrote:
Hello,
I have a data frame which looks like
head(d)
a1 a2 n j col
1 1 1 88341002 11 #E7E7E7
2 1 2 25094882 11 #E7E7E7
3 1 3 16916246 11 #E7E7E7
4 1 4 14289229 11 #E7E7E7
5 1 5 11945929 11 #E7E7E7
6 1 6 8401235 11 #E7E7E7
The values in 'j' run from 1 to 11. I would like to plot the point
(a1,a2)
with color given by j
I tried
mi <-
image(d[,"a1"],d[,"a2"],d[,"j"],col=mycols(length(f)),useRaster=TRUE)
(where mycols is from
colorRampPalette(c("#000000","#FFFFFF"),bias=1.5)
However, i got the following error:
Error in image.default(d[, "a1"], d[, "a2"], d[, "j"], col =
mycols(length(f)), :
increasing 'x' and 'y' values expected
What am i doing wrong here? I have a million points and so would
like to
write to a png or jpeg file.
It is difficult to tell. We do not have either dput(head(d)) or str(d)
so some of the potential newbie R potholes remain over the horizon of
our sight. The z-argument is supposed to be a matrix while x and y are
supposed to be the locations of the grid, so perhaps you need to call
image() like:
?image
image(x=unique(d[,"a1"]),
y=unique(d[,"a2"]),
z=matrix( d[,"j"], nrow=length( unique(d[,"a1"]) ),
ncol=length( unique(d[,"a2"]) )
),
... <other-args>...
)
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David Winsemius, MD
West Hartford, CT
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