playwith (version 0.8-56)

playPointInput: Get point, line or rect input from playwith user

Description

Part of the playwith Application Programming Interface.

Usage

playPointInput(playState, prompt = "Click on the plot")
playLineInput(playState, prompt = "Click and drag to define a line")
playRectInput(playState, prompt = "Click and drag to define a rectangular region",
	scales = c("x", "y"))

Arguments

playState

a playState object representing the plot, window and device.

prompt

text to display in the prompt.

scales

one or more of "x" and "y", constraining the dimensions of the region to select. E.g. if scales="x" then a section along the x-axis is selected, as might be appropriate for a time series.

Value

• All these functions return NULL if the user cancelled (e.g. by right-clicking). The return value is a list with:
• space
  character, specifies the plot space in which the user clicked or dragged. See the space argument to playDo.
• coords
  native coordinates of the point or shape in space. A list with numeric vectors x and y. For a rectangle or line, these are length 2 where the first element refers to the start of the drag motion. For a point these are length 1. If space is "page", this is NULL.
• dc
  device coordinates of the point or shape (pixels).
• ndc
  normalised device coordinates of the point or shape.
• is.click
  logical, whether it was a click (so probably should not be treated as a rectangle or line). This is not returned by playPointInput.
• modifiers
  a flag representing which modifier keys were pressed during the click (or at the end of a drag). E.g. to test for Shift key: if (foo$modifiers & GdkModifierType["shift-mask"]). See enums-and-flags.

Details

playPointInput is similar to locator, but returns native coordinates in whichever plot space was clicked on. Device coordinates and normalised device coordinates are also available. playRectInput and playLineInput allow the user to interactively draw a rectangle or line.

See Also

playSelectData, playwith.API

Examples

if (interactive()) {

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

}