plgraphics (version 1.2)

plcond: Plot Two Variables Conditional on Two Others

Description

A scatterplot matrix is generated that shows, in each panel, the relationship between two primary variables, with the dataset restricted by appropriate subranges of two 'conditioning' variables. This corresponds to link{coplot}. The points that are near to the the 'window' defining the panel's restriction are also shown, in a distinct style.

Usage

plcond(x, y = NULL, condvar = NULL, data = NULL,
  panel = NULL, nrow = NULL, ncol = NULL,
  xaxmar = NULL, yaxmar = NULL, xlab = NULL, ylab = NULL,
  oma = NULL, plargs = NULL, ploptions = NULL, assign = TRUE, ...)

Value

None.

Arguments

x, y

the two variables used to generate each panel. They may be specified as vectors, as column names of data or by formulas as in plyx.

condvar

two (or one) variables that define the restrictions of the data for the different panels. A numerical variable is cut into intervals, see Details. A factor defines the 'ranges' as its levels. For each combination of intervals or levels of the two variables, a panel is generated.

data

data.frame in which the variables are found if needed

panel

function that generates each panel. If set by the user, it must accept the arguments x, y, ckeyx, ckeyy, pcol, pale, cex, smooth, smooth.minobs, ploptions. The default is ploptions("plcond.panel"), which in turn is initiated as the function plpanelCond.

nrow, ncol

number of maximum rows and columns on a page

xaxmar, yaxmar

margin in which the axis (tick marks and corresponding labels) should be shown: either 1 or 3 for xaxmar and 2 or 4 for yaxmar.

xlab, ylab

labels of the variables x and y

oma

width of outer margins, see par. Note that a minimum of 2.1 is generally needed for showing tick and axis labels.

plargs

result of calling pl.control. If NULL, pl.control will be called to generate it. If not null, arguments given in ... will be ignored.

ploptions

list of pl options.

assign

logical: Should the plargs be stored in pl.envir?

...

further arguments passed to the panel function and possibly further to functions called by the panel function.

Author

Werner A. Stahel

Details

A numerical conditioning variable (condvar) will be split by default into classes by splitting its robust range (robrange) into ploptions("plcond.nintervals") equally long intervals. Alternatively, the variable may contain an attribute cutpoints which then defines the intervals.

For numerical conditioning variables, each panel also shows neighboring points with a different color and diminished size. The size of the neighborhood is defined by the proportion of extension ploptions("plcond.ext"). The point size of the respective 'exterior' points is given by ploptions("plcond.cex") The color are given by the 4 elements of ploptions("plcond.col"): The first element is used to paint the neighboring points to the left of the current range of the conditioning x variable, the second element paints those to the right, and the third and fourth are used in the same way for the conditioning y variable. The neighboring points that are outside both ranges get a color mixing the two applicable colors according to this rule. Finally, paling is applied to these colors with a degree that is linear in the distance from the interval, determined by the range given by ploptions("plcond.pale").

See Also

coplot

Examples

plcond(Sepal.Width~Sepal.Length, data=iris, condvar=~Species+Petal.Length)