playSelectData: Let playwith user select data points

Description

Part of the playwith Application Programming Interface.

Usage

playSelectData(playState = playDevCur(),
    prompt = paste("Click or drag to select data points;",
                   "Right-click or Esc to cancel."),
    scales = "dynamic",
    foo = playRectInput(playState, prompt = prompt, scales = scales))

Arguments

playState

a playState object representing the plot, window and device.

prompt

text to display in the prompt.

scales

the default allows the user to hold Shift while dragging, to constrain the selection to x or y scales. Otherwise this should be one or more of "x" and "y", specifying which axes to select along.

foo

rectangular plot region structure, usually generated interactively.

Value

playSelectData returns NULL if the user cancelled (e.g. by right-clicking). Otherwise a list with:
spacecharacter, specifies the plot space in which data points were selected. See the space argument to playDo.
subscriptsindices of the data points selected. This relies on the data being guessed correctly from the plot call, unless data.points was specified explicitly.
x, yvalues of the selected data points.
is.clicklogical, whether it was a click (otherwise a drag).
posposition of click relative to the closest point, as in the pos argument to text. If is.click is false, this is NULL.
...as well as all the other elements returned by playRectInput.

Details

playSelectData is similar to identify. The user is prompted to click or drag to select data points. If a click, the nearest point is selected, if it is within 11 points. If it is a drag, all points within the rectangular region are selected. Note that data points can be selected from one panel of a multi-panel lattice plot without specifying the panel beforehand.

Examples

Run this code

if (interactive()) {

library(lattice)
playwith(xyplot(Sepal.Width ~ Petal.Width | Species, data = iris))
playSelectData()

}