coplot {base}R Documentation

Conditioning Plots

Description

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

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 recycled.
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.

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, ...))
detach() # data.frame(state.x77)
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