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 = c(x.name, paste("Given :", a.name)),
           ylab = c(y.name, paste("Given :", b.name)),
           subscripts = FALSE,
           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; labels to use for the x axis and the first conditioning variable. If only one label is given, it is used for the x axis and the default label is used for the conditioning variable.
`ylab` | character; labels to use for the y axis and any second conditioning variable.
`subscripts` | logical: if true the panel function is given an additional (third) argument `subscripts` giving the subscripts of the data passed to that panel.
`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.

### Details

In the case of a single conditioning variable `a`, when both `rows` and `columns` are unspecified, a ``close to square'' layout is chosen with `columns >= rows`.

In the case of multiple `rows`, the order of the panel plots is from the bottom and from the left (corresponding to increasing `a`, typically).

### 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.v=given.depth, rows=1)

    ## 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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