Conditioning Plots

Usage

coplot(formula, data, given.values, panel = points, rows, columns,
       show.given = TRUE, col = par("fg"), pch = par("pch"),
       xlab = paste("Given :", a.name),
       ylab = paste("Given :", b.name),
       number = 6, overlap = 0.5, ...)
co.intervals(x, number = 6, overlap = 0.5)

Arguments

formula a formula describing the form of conditioning plot. A formula of the form y ~ x | a indicates that plots of y versus x should be produced conditional on the variable a. A formula of the form y ~ x| a * b indicates that plots of y versus x should be produced conditional on the two variables a and b.

x and y must be numeric, but a and b may be either numeric or factors.

data a data frame containing values for any variables in the formula. By default the environment where coplot was called from is used.
given.values a value or list of two values which determine how the conditioning on a and b is to take place.

When there is no b (i.e., conditioning only on a), usually this is a matrix with two columns each row of which gives an interval, to be conditioned on, but is can also be a single vector of numbers or a set of factor levels (if the variable being conditioned on is a factor). In this case (no b), the result of co.intervals(..) can be used directly as given.values argument.

panel a function(x,y, col, pch, ...) which gives the action to be carried out in each panel of the display. The default is points.
rows the panels of the plot are laid out in a rows by columns array. rows gives the number of rows in the array.
columns the number of columns in the panel layout array.
show.given logical (possibly of length 2 for 2 conditioning variables): should conditioning plots be shown for the corresponding conditioning variables (default TRUE)
col a vector of colors to be used to plot the points. If too short, the values are recycled.
pch a vector of plotting symbols or characters. If too short, the values are recycyled.
xlab character; label to use for the 1st conditioning variable.
ylab character; label to use for the 2nd conditioning variable.
number integer; the number of conditioning intervals, possibly of length 2 for x and y direction.
overlap numeric < 1; the fraction of overlap of the conditioning variables, possibly of length 2 for x and y direction. When overlap < 0, there will be gaps between the data slices.
... additional arguments to the panel function.

Description

This function produces two variants of the conditioning plots discussed in the reference below.

Value

co.intervals(., number, .) returns a (number x 2) matrix, say ci, where ci[k,] is the range of x values for the k-th interval.

References

Cleveland, W. S. (1993). Visualizing Data. New Jersey: Summit Press.

See Also

pairs, panel.smooth, points.

Examples

## Tonga Trench Earthquakes
data(quakes)
coplot(long ~ lat | depth, data = quakes)
given.depth <- co.intervals(quakes$depth, number=4, overlap=.1)
coplot(long ~ lat | depth, data = quakes, given.values=given.depth)

## Conditioning on 2 variables:
ll.dm <- long ~ lat | depth * mag
coplot(ll.dm, data = quakes)
coplot(ll.dm, data = quakes, number=c(4,7), show.given = c(T,F))
coplot(ll.dm, data = quakes, number=c(3,7),
       overlap=c(-.5,.1)) # negative overlap DROPS values

data(warpbreaks)
## given two factors
coplot(breaks ~ 1:54 | wool * tension, data = warpbreaks, col = 'red')

## Example with empty panels:
data(state)
attach(data.frame(state.x77))#> don't need `data' arg. below
coplot(Life.Exp ~ Income | Illiteracy * state.region, number = 3,
       panel=function(x,y,...) panel.smooth(x,y, span= .8, ...))

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