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>...
)
> [[alternative HTML version deleted]]
You can thank us by starting to post in plain text.
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html... and
> and provide commented, minimal, self-contained, reproducible code.
--
David Winsemius, MD
West Hartford, CT
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https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide
http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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