plotrix (version 3.8-4)

maxEmptyRect: Find an empty space on a plot

Description

Try to find the largest empty rectangle on a plot.

Usage

maxEmptyRect(ax,ay,x,y)

Value

A list containing the area of the rectangle and the coordinates of the lower left and upper right corners (as used in rect) of the rectangle found.

Arguments

ax,ay

The rectangle within which all of the points are contained. Usually the limits of a plot.

x,y

x and y positions of the points.

Author

Hans Borchers

Details

maxEmptyRect searches the pairs of points on the plot to find the largest rectangular space within which none of the points lie. It does not guarantee that the space will be large enough to fit a legend or text.

Two alternatives are the largest.empty function in the Hmisc package and the emptyspace function. maxEmptyRect appears to outperform emptyspace, particularly in running time. However, emptyspace will sometimes find a "squarer" rectangle when maxEmptyRect finds a slightly larger narrow rectangle.

References

A. Naamad, D. T. Lee, and W.-L. Hsu (1984). On the Maximum Empty Rectangle Problem. Discrete Applied Mathematics, 8: 267-277.

Examples

 x<-runif(100)
 y<-runif(100)
 plot(x,y,main="Find the maximum empty rectangle",xlab="X",ylab="Y")
 mer<-maxEmptyRect(c(0,1),c(0,1),x,y)
 rect(mer$rect[1],mer$rect[2],mer$rect[3],mer$rect[4],border="red")