ixyplot {IDPmisc}R Documentation

Image Scatter Plot for Large Datasets

Description

Produces an image scatter plot of large datasets where the colors encode the density of the points in the scatter plot. Works also with factors.

Usage

ixyplot(x, y = NULL,
        pixs = 1, zmax = NULL, colramp = IDPcolorRamp, border = FALSE,
        xlab = NULL, ylab = NULL, nx.lab = 5, ny.lab = 5,
        main = NULL, cex.main = par("cex.main"))

Arguments

x Object of dimension (n,1) or (n,2) when y not present.
Vector of length(n) when y present.
y Vector of length n or NULL.
pixs Pixelsize in mm.
zmax Maximum counts per pixel to be plotted. zmax must be >= maximum number of counts per pixel.
colramp Color ramp to encode the density of the points within a pixel.
border Shall border be drawn between the colors in the legend: TRUE / FALSE.
xlab Label for x-axis.
ylab Label for y-axis.
nx.lab Approximate number of labeled ticks on x-axis.
ny.lab Approximate number of labeled ticks on y-axis.
main Title.
cex.main Size of title relative to par("cex")

Details

The idea is similar to plot.hexbin. The hexagons are better suited to reflect the density of points in a plane than the squares used here. Nevertheless squares are, contrary to hexagons, invariant to reflexions at the x- and y-axis and therefore suited for scatter plot matrices and also for plotting factors.

Value

Maximum number of counts per Pixel found.

Note

When you get the error message "Zmax too small! Densiest aereas are out of range!" you must run the function again without specifying zmax. The value returned gives you the minimum value allowed for zmax.

Author(s)

Andreas Ruckstuhl, refined by Rene Locher

See Also

ilagplot, ipairs, Image

Examples

x <-  rnorm(100000)
y <- atan(rnorm(100000,0))
ixyplot(x,y)
ixyplot(x,pixs=2)
ixyplot(iris[,1:2],pixs=4)
ixyplot(iris[,"Petal.Width"],iris[,"Species"],pixs=4)
ixyplot(x=iris[,"Species"],y=iris[,"Petal.Width"],pixs=4,border=TRUE,
        xlab="Species",
        ylab="Petal Width",
        main="Iris Species and Petal Width")

[Package IDPmisc version 0.3.1 Index]