Show overlying points as counts

count.overplot checks for overlying points defined as points separated by a maximum of tol, a two element numeric vector of the x and y tolerance. Defaults to 1/2 of the width of a lower case "o" in the x direction and 1/2 of the height of a lower case "o" in the y direction.

count.overplot(x,y,tol=NULL,col=par("fg"),pch="1",...)

Arguments

x,y

Two numeric data vectors or the first two columns of a matrix or data frame. Typically the x/y coordinates of points to be plotted.

tol

The largest distance between points that will be considered to be overlying.

col

Color(s) for the points (not the numbers).

pch

Symbol(s) to display.

...

additional arguments passed to plot.

Value

nil

Author

Jim Lemon

See also

cluster.overplot,sizeplot

Examples

 xy.mat<-cbind(sample(1:10,200,TRUE),sample(1:10,200,TRUE))
 count.overplot(xy.mat,main="count.overplot",
  xlab="X values",ylab="Y values")
#> Error in strwidth("o"): plot.new has not been called yet