xyTable {grDevices}  R Documentation 
Given (x,y) points, determine their multiplicity – checking for equality only up to some (crude kind of) noise. Note that this is special kind of 2D binning.
xyTable(x, y = NULL, digits)
x, y 
numeric vectors of the same length; alternatively other
(x, y) argument combinations as allowed by

digits 
integer specifying the significant digits to be used for
determining equality of coordinates. These are compared after
rounding them via 
A list with three components of same length,
x 
x coordinates, rounded and sorted. 
y 
y coordinates, rounded (and sorted within 
number 
multiplicities (positive integers); i.e.,

sunflowerplot
which typically uses
xyTable()
; signif
.
xyTable(iris[, 3:4], digits = 6)
## Discretized uncorrelated Gaussian:
require(stats)
xy < data.frame(x = round(sort(rnorm(100))), y = rnorm(100))
xyTable(xy, digits = 1)