R: Constructors for widgets to select a value from a sequence.

gslider {gWidgets} | R Documentation

## Constructors for widgets to select a value from a sequence.

### Description

The gslider widget and gspinbutton widget allow the user to select a value from a sequence using the mouse. In the slider case, a slider is dragged left or right (or up or down) to change the value. For a spin button a text box with arrows beside allow the user to scroll through the values by clicking the arrows.

Some toolkits only allow integer values for these.

### Usage

    gslider(from = 0, to = 100, by = 1, length.out=NULL, along.with=NULL,
    value = from[1], horizontal = TRUE, handler = NULL, action = NULL,
    container = NULL, ..., toolkit = guiToolkit())

    gspinbutton (from = 0, to = 10, by = 1, length.out=NULL, along.with=NULL,
    value = from, digits = 0,
        handler = NULL, action = NULL, container = NULL, ..., toolkit = guiToolkit())

### Arguments

`from` | Starting point in range. For `glider`, this may be a vector of values that can be sorted from `sort(unique(...))`. In this case, `to`, `by`, etc. are ignored.
`to` | Ending point in range
`by` | Step size between values in the sequence
`length.out` | In place of by, take number of steps from this
`along.with` | In place of length.out, take length from this vector
`value` | The initial value
`digits` | The number of digits shown
`horizontal` | Specifies orientation of gslider widget
`handler` | Called on a change event.
`action` | Passed to handler
`container` | Optional container to attach widget to
`...` | Passed to `add` method of container
`toolkit` | Which GUI toolkit to use

### Details

Widgets to select from a vector of values. This vector is usually a sequence, as is returned by `seq`, hence the similar arguments, although the implementation is a bit less general, as `length.out` and `along.with` are used to compute `by` when given.

For `gslider` any ordered vector may be used if specified to `from`. Some toolkits only allow integer sequences, see the respective gWidgetsXXX packages for details.

The `svalue` method returns the selected value. If all values are specified to `from`, then `index` argument is respected.

The `svalue<-` method is used to set the selected value. If all values are specified to `from`, then `index` argument is respected.

The `[<-` method can be used to change the sequence that the value is selected from. It expects a regular sequence, or if all values were originally specified to `from` a sortable sequence.

The `addhandlerchanged` handler is called when the widgets' value is changed.

### Examples

    ## Not run:
      x <- rnorm(100)

      ## our handler
      plotHist <- function(...)
        hist(x, col=gray(svalue(sb)), breaks = svalue(sl))

      w <- gwindow("Slider and spinbox example")
      tbl = glayout(container=w)
      tbl[1,1] <- "Slide value to adjust shade"
      tbl[1,2] <- (sb <- gspinbutton(from=0,to=1,by=0.05,value=.5, container=tbl,
        handler=plotHist))
      tbl[2,1] <- "No. breaks"
      tbl[2,2, expand=TRUE] <- (sl <- gslider(from = 1, to= 100, by=1, value = 10,
        container = tbl, handler = plotHist))

    ## update slider using [<-
      sl[] <- seq(2,50, by=2)

      ## other sequence:
      w <- gwindow("Slider with sequence")
      sl <- gslider(letters, container=w)
      svalue(sl, index=TRUE)
      svalue(sl) <- "m"
      sl[] <- LETTERS ## can be sorted via sort(unique(LETTERS))

    ## End(Not run)

[Package gWidgets version 0.0-54 Index]