Select variables from a data frame — varSelectInput

varSelectInput(
  inputId,
  label,
  data,
  selected = NULL,
  multiple = FALSE,
  selectize = TRUE,
  width = NULL,
  size = NULL
)

varSelectizeInput(inputId, ..., options = NULL, width = NULL)

Arguments

inputId	The `input` slot that will be used to access the value.
label	Display label for the control, or `NULL` for no label.
data	A data frame. Used to retrieve the column names as choices for a `selectInput()`
selected	The initially selected value (or multiple values if `multiple = TRUE`). If not specified then defaults to the first value for single-select lists and no values for multiple select lists.
multiple	Is selection of multiple items allowed?
selectize	Whether to use selectize.js or not.
width	The width of the input, e.g. `'400px'`, or `'100%'`; see `validateCssUnit()`.
size	Number of items to show in the selection box; a larger number will result in a taller box. Not compatible with `selectize=TRUE`. Normally, when `multiple=FALSE`, a select input will be a drop-down list, but when `size` is set, it will be a box instead.
...	Arguments passed to `varSelectInput()`.
options	A list of options. See the documentation of selectize.js for possible options (character option values inside `base::I()` will be treated as literal JavaScript code; see `renderDataTable()` for details).

Description

Create a select list that can be used to choose a single or multiple items from the column names of a data frame.

Value

A variable select list control that can be added to a UI definition.

Details

By default, varSelectInput() and selectizeInput() use the JavaScript library selectize.js (https://github.com/selectize/selectize.js) to instead of the basic select input element. To use the standard HTML select input element, use selectInput() with selectize=FALSE.

Note

The variable selectize input created from varSelectizeInput() allows deletion of the selected option even in a single select input, which will return an empty string as its value. This is the default behavior of selectize.js. However, the selectize input created from selectInput(..., selectize = TRUE) will ignore the empty string value when it is a single choice input and the empty string is not in the choices argument. This is to keep compatibility with selectInput(..., selectize = FALSE).

Server value

The resulting server input value will be returned as:

A symbol if multiple = FALSE. The input value should be used with rlang's rlang::!!(). For example, ggplot2::aes(!!input$variable).
A list of symbols if multiple = TRUE. The input value should be used with rlang's rlang::!!!() to expand the symbol list as individual arguments. For example, dplyr::select(mtcars, !!!input$variabls) which is equivalent to dplyr::select(mtcars, !!input$variabls[[1]], !!input$variabls[[2]], ..., !!input$variabls[[length(input$variabls)]]).

Examples

## Only run examples in interactive R sessions
if (interactive()) {

library(ggplot2)

# single selection
shinyApp(
  ui = fluidPage(
    varSelectInput("variable", "Variable:", mtcars),
    plotOutput("data")
  ),
  server = function(input, output) {
    output$data <- renderPlot({
      ggplot(mtcars, aes(!!input$variable)) + geom_histogram()
    })
  }
)


# multiple selections
if (FALSE) {
shinyApp(
 ui = fluidPage(
   varSelectInput("variables", "Variable:", mtcars, multiple = TRUE),
   tableOutput("data")
 ),
 server = function(input, output) {
   output$data <- renderTable({
      if (length(input$variables) == 0) return(mtcars)
      mtcars %>% dplyr::select(!!!input$variables)
   }, rownames = TRUE)
 }
)}

}