[R] Plotting sum rather than count in hexbin

[Jim Lemon]

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