R help - Oct 2014 - Plotting sum rather than count in hexbin

Hi everyone,

This may be a trivial solution but I would appreciate any help.

I have a database with three variables. I would like to plot the first two
variables in a xy plot making the color of points proportional to the values in
the third variable. Given that many points overlap, I decided to use the hexbin
package, which allows aggregating the points by a third variable.
I figured out how to make the sums by hexbins but I am falling short in how to
link the sums back to the hexbins and then plot the hexbins color coded by the
sums?.  Below is the code so far.

Thanks,

Camilo



library(hexbin)


#generates data for three variables
dat=data.frame(    x = c(rep(1:10,3)),
                                    y = c(rep(1:10,3)),
                                    z = c(rep(1:10,3)))

#generates hexbin with the x and y variables
hbin<-hexbin(dat$x, dat$y, xbins=10, IDs=TRUE)

#sum values of points inside hexbins
SumHexBin<-hexTapply(hbin, dat$z, sum)


#the question is how to link the SumHexBin back to the hbin and then plot it
color coding bins by the sums?



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On Sun, 19 Oct 2014 08:09:28 AM Camilo Mora wrote:
> Hi everyone,
> 
> This may be a trivial solution but I would appreciate any help.
> 
> I have a database with three variables. I would like to plot the first 
two
> variables in a xy plot making the color of points proportional to the
> values in the third variable. Given that many points overlap, I 
decided to
> use the hexbin package, which allows aggregating the points by a 
third
> variable. I figured out how to make the sums by hexbins but I am 
falling
> short in how to link the sums back to the hexbins and then plot the 
hexbins
> color coded by the sums?.  Below is the code so far.
> 
> Thanks,
> 
> Camilo
> 
> 
> 
> library(hexbin)
> 
> 
> #generates data for three variables
> dat=data.frame(    x = c(rep(1:10,3)),
>                                     y = c(rep(1:10,3)),
>                                     z = c(rep(1:10,3)))
> 
> #generates hexbin with the x and y variables
> hbin<-hexbin(dat$x, dat$y, xbins=10, IDs=TRUE)
> 
> #sum values of points inside hexbins
> SumHexBin<-hexTapply(hbin, dat$z, sum)
> 
> 
> #the question is how to link the SumHexBin back to the hbin and 
then plot it
> color coding bins by the sums?
> 
Hi Camilo,
The color.scale function (plotrix) will convert numeric values into colors 
in a number of ways. I think you want the names of SumHexBin as 
numbers, so a simple way is:

library(plotrix)
hbincol<-color.scale(as.numeric(names(SumHexBin)),
 extremes=c("red","green"))

Jim