Apply function to data from each hexagon bin.

A wrapper for tapply except that it operates with each hexagon bin being the category. The function operates on the data associated on the points from each bin.

hexTapply(hbin, dat, FUN = sum, ..., simplify=TRUE)

Arguments

hbin

a object of class "hexbin", typically produced by hexbin(*).

dat

A vector of data the same length as hbin@cID

FUN

the function to be applied. In the case of functions like +, %*%, etc., the function name must be quoted. If FUN is NULL, tapply returns a vector which can be used to subscript the multi-way array tapply normally produces.

...

optional arguments to FUN.

simplify

If FALSE, tapply always returns an array of mode "list". If TRUE (the default), then if FUN always returns a scalar, tapply returns an array with the mode of the scalar.

Details

This function is a wrapper for tapply, except that the cell id is always the categorical variable. This function is specifically good for adding variables to the cAtt slot of a hexbin object or for plotting a third variable in a hexagon plot. See below for examples.

Value

Returns a vector of the result of 'FUN' as in

tapply. See tapply for detailed description of output.

Author

Nicholas Lewin-Koh

See also

tapply,hexbin

Examples

  data(NHANES)
  hbin<-hexbin(log(NHANES$Diet.Iron+1),log(NHANES$BMI),xbins=25,IDs=TRUE)
  hvp<-plot(hbin)
  mtrans<-hexTapply(hbin,NHANES$Transferin,median,na.rm=TRUE)
  pushHexport(hvp$plot.vp)
  grid.hexagons(hbin,style='lattice',pen=0,border='red',use.count=FALSE,
cell.at=mtrans)