sliding window over a large vector

Because I had too much time on my hands, here's a little function that 
will do whatever you want over a window you specify. No, I haven't done 
any time trials :-(


# my  own boxcar tool, just because.
# use bfunc to specify what function to apply to the windowed
# region.
boxcar<-function(x, width=5, bfunc='mean'){
	
	bfunc<-get(bfunc)
	
	boxout<-mapply(function(shiftx) {
		bfunc(window(x,shiftx,shiftx+width))
		
		} ,seq(1,(length(x)-width))
	
	return(invisible(boxout))
	}