hexTapply {hexbin}

Apply function to data from each hexagon bin.

Description

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.

Usage

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(s)

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)