gradio {gWidgets2} | R Documentation

## Constructor for radio button widget

### Description

A radio button group allows a user to select one from many items. In gWidgets2 the radio button widget shows 2 or more items. The items are coerced to characters, usually by the underlying toolkit. Use the `coerce_with` property to set a function, such as `as.numeric`, to coerce the return value during the `svalue` code. The items are referred to with the `[` method, the selected one with `svalue`.

Generic for method dispatch

The svalue method returns the radio button label or its index if `index=TRUE`. Labels are coerced to character by many of the toolkits. To be sure to return a numeric value, one can assign to the `coerce_with` property, e.g., `obj$coerce_with <- as.numeric`. For all widgets, if a function is specified to `coerce_with` it will be called on the value returned by `svalue`.

For a radio button group, for `svalue` the value can be referred to by index or label.

Check for repeated items before passing on to `set_items`

### Usage

    gradio(items, selected = 1, horizontal = FALSE, handler = NULL,
      action = NULL, container = NULL, ..., toolkit = guiToolkit())

    .gradio(toolkit, items, selected = 1, horizontal = FALSE, handler = NULL,
      action = NULL, container = NULL, ...)

    ## S3 method for class 'GRadio'
    svalue(obj, index = NULL, drop = TRUE, ...)

    ## S3 replacement method for class 'GRadio'
     svalue(obj,index=NULL,drop=TRUE,...) <- value

    ## S3 replacement method for class 'GRadio'
     x[i, j, ...] <- value

### Arguments

`items` | items to select from
`selected` | index of initially selected item
`horizontal` | layout direction
`handler` | A handler assigned to the default change signal. Handlers are called when some event triggers a widget to emit a signal. For each widget some default signal is assumed, and handlers may be assigned to that through `addHandlerChanged` or at construction time. Handlers are functions whose first argument, `h` in the documentation, is a list with atleast two components `obj`, referring to the object emitting the signal and `action`, which passes in user-specified data to parameterize the function call. Handlers may also be added via `addHandlerXXX` methods for the widgets, where `XXX` indicates the signal, with a default signal mapped to `addHandlerChanged` (cf. `addHandler` for a listing). These methods pass back a handler ID that can be used with `blockHandler` and `unblockHandler` to suppress temporarily the calling of the handler.
`action` | User supplied data passed to the handler when it is called
`container` | A parent container. When a widget is created it can be incorporated into the widget heirarchy by passing in a parent container at construction time. (For some toolkits this is not optional, e.g. gWidgets2tcltk or gWidgets2WWW2.)
`...` | These values are passed to the `add` method of the parent container. Examples of values are `expand`, `fill`, and `anchor`, although they're not always supported by a given widget. For more details see add. Occasionally the variable arguments feature has been used to sneak in hidden arguments to toolkit implementations. For example, when using a widget as a menubar object one can specify a parent argument to pass in parent information, similar to how the argument is used with gaction and the dialogs.
`toolkit` | Each widget constructor is passed in the toolkit it will use. This is typically done using the default, which will lookup the toolkit through `guiToolkit`.
`obj` | object of method call
`index` | NULL or logical. If `TRUE` and widget supports it an index, instead of a value will be returned.
`drop` | NULL or logical. If widget supports it, drop will work as it does in a data frame or perhaps someother means.
`value` | items to assigns a choices for the buttons
`x` | `GRadio` object
`i` | button index. Leavel as missing to replace items to select from.
`j` | ignored

### Examples

    if(interactive()) {
      w <- gwindow("Selection widgets")
      g <- gvbox(cont=w)

      fl <- gformlayout(cont=g)
      gcheckbox("checkbox", checked=TRUE, cont=fl, label="checkbox")
      gradio(state.name[1:4], selected=2, horizontal=TRUE, cont=fl, label="gradio")
      gcheckboxgroup(state.name[1:4], horizontal=FALSE, cont=fl, label="checkbox group")

      bg <- ggroup(cont=g)
      gbutton("ok", cont=bg, handler=function(h,...) print(sapply(fl$children, svalue)))

    }

[Package gWidgets2 version 1.0-8 Index]