ipairs {IDPmisc} | R Documentation |
Produces an image scatter plot matrix of large datasets where the colors encode the density of the points in the scatter plots.
ipairs(x, pixs = 1, zmax = NULL, ztransf=function(x){x}, colramp = IDPcolorRamp, border = FALSE, labels, cex.lab = NULL, nlab = 5, minL.lab = 2, pty = "s", main = NULL, cex.main = par("cex.main"), verbose = FALSE, ...)
x |
data.frame or matrix |
pixs |
Pixel size in mm on the plotting device. |
zmax |
Maximum counts per Pixel to be plotted. When NULL each scatter plot has its individual scale. If a number >= maximum number of counts per pixel is supplied, the scale will be identical for all scatter plots. The maximum of the number per pixel is delivered by the return value. |
ztransf |
Function to transform the counts. The user has to make sure that the transformed counts lie in the range [0,zmax], where zmax is any positive number (>=2). |
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 . |
labels |
Labels of columns. If NULL the names of x are used. |
minL.lab |
The minimum length of the abbreviations of factor levels, used to label the axes. |
cex.lab |
Size of the labels. If NULL they are calculated automatically. |
nlab |
Approximate number of labels on axes. |
pty |
See Argument pty in par . |
main |
Titel. |
cex.main |
Size of title. |
verbose |
When verbose == TRUE , the values for
cex.main and cex.lab are returned in addition to zmax . |
... |
Additional arguments to plot.default |
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.
The code is based on R function pairs
V1.7.
Maximum number of counts per Pixel found. Additional elements are
returned when verbose == TRUE
.
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.
Andreas Ruckstuhl, Rene Locher
zmax <- ipairs(airquality,pixs=2,main="Air Quality") ipairs(airquality,pixs=2,zmax=zmax,border=TRUE) ## example with factors zmax <- ipairs(iris,pixs=2) ipairs(iris,pixs=2,zmax=zmax) ## a really huge dataset if(require(SwissAir)) { data(AirQual) ## low correlation ipairs(AirQual[,c("ad.O3","lu.O3","sz.O3")], ztransf=function(x){x[x<1] <- 1; log2(x)*10}) ipairs(AirQual[,c("ad.NO","lu.NO","sz.NO")], ztransf=function(x){x[x<1] <- 1; log2(x)*10}) ## high correlation Ox <- AirQual[,c("ad.O3","lu.O3","sz.O3")]+ AirQual[,c("ad.NOx","lu.NOx","sz.NOx")]- AirQual[,c("ad.NO","lu.NO","sz.NO")] names(Ox) <- c("ad","lu","sz") ipairs(Ox,cex.lab=2, ztransf=function(x){x[x<1] <- 1; log2(x)*10}) ## cf. ?AirQual for the explanation of the physical and ## chemical background } else print("Package SwissAir is not available")