Allow duplicate selections with InputSelect

[TearsRfuel]

Please allow the option for selectInput / selectizeInput to select the same items repeatedly. There are applications where this is needed. The selection list should remain unchanging.

Thats basically all. Thank you

[gadenbuie]

Could you give an example that motivates the feature request? Even better would be to include a small app as well.

[TearsRfuel]

Could you give an example that motivates the feature request? Even better would be to include a small app as well.

In my case, I am creating an application to visualize win-rate data for competitive gaming. In this case, teams can choose their character prior to the match, and these characters can be identical. I.e. you can have a matchup of A+A vs B+B and users might like to know what the win rate of A+A vs B+B is. There was actually a similar request here: #2939

So in this example app, the user might want to select A, B, C or D twice

choices <- c("A", "B", "C", "D")
ui <- fluidPage(
  selectizeInput(inputId = "choose_your_character", 
              "your character(s)",
              choices = choices,
              options = list(maxItems = 2),
              multiple = TRUE)
)

server <- function(input, output, session) {

}

shinyApp(ui, server)

Thank you

[gadenbuie]

Here's a version (try it on shinylive.io) building on the solution provided in #2939 that updates the select input with new choices based on the original choice values so that the options "A", "B", "C" and "D" always appears as choices.

library(shiny)

choices <- setNames(nm = c("A", "B", "C", "D"))

clean_choices <- function(x) {
  # removes the extra index we add to each choice
  sub("__\\d+__$", "", x)
}

new_choices <- function(current) {
  cli::cli_inform("-----")
  cli::cli_inform("current: {.val {current}}")
  cli::cli_inform("clean: {.val {clean_choices(current)}}")
  
  selected <- unique(clean_choices(current))
  
  if (length(selected) == 0) {
    # Nothing selected, return base choices
    return(choices)
  }

  choices_not_selected <- setdiff(choices, selected)
  new_choices <- sprintf(
    "%s__%d__",
    selected,
    floor(runif(1) * 1e5) # A random id for the new choice
  )
  cli::cli_inform("new choices: {.val {new_choices}}")

  # New choices must include the current selection, plus the new
  # choices to fill in for what's been selected, plus the base
  # original choices.
  x <- union(current, new_choices)
  x <- union(choices, x)
  x <- sort(x)
  names(x) <- clean_choices(x)
  cli::cli_inform("updated choices: {.val {x}}")
  x
}

ui <- fluidPage(
  selectizeInput(
    inputId = "choose_your_character", 
    "your character(s)",
    choices = choices,
    options = list(maxItems = 10, plugins = "remove_button"),
    multiple = TRUE
  ),
  verbatimTextOutput("debug")
)

server <- function(input, output, session) {
  observe({
    updateSelectInput(
      session,
      "choose_your_character",
      choices = new_choices(input$choose_your_character),
      selected = isolate(input$choose_your_character)
    )
  })

  output$debug <- renderPrint({
    req(input$choose_your_character)
    picked <- clean_choices(input$choose_your_character)
    cat("You've picked", paste(picked, collapse = ", "))
  })
}

shinyApp(ui, server)

Clearly, this isn't the most ideal solution, but it solves the problem at hand. I'd prefer an upstream feature in selectize.js, but that seems unlikely. I'd recommend rolling this into a Shiny module if you plan to use it in your own app.

[ismirsehregal]

In a scenario like this maybe shinyjqui (see orderInput()) or sortable are more suitable.