How to get a specific value instead of the printed name, of choices, in R Shiny select-Input

Question

I am building a Shiny app, where I have a selectizeInput. The options to select are country Names, stored in a data.frame along their three-digit codes.

Country

name	code
Aruba	ABW
Afghanistan	AFG
...	...

In my shiny app, I call selectizeInput, in the UI-part like this:

selectizeInput(inputId = 'inSelect',
               label = "countries",
               choices = country$name,
               multiple = TRUE,
               options = list(maxItems = 4, 
               placeholder = 'select up to 4 countries'))

When selecting countries, I get a list of the names of them in the inSelect variable.

e.g. when I select Afghanistan, inSelect has the Value Afghanistan.

Is there a possibility, to get a different Value as the output. So not the Name, but the code, stored next to it in the Table?

e.g. when I select Afghanistan, InSelect gets the Value AFG.

I know, that I can write the choice names down alongside their values. But Country is a table of ~200 rows.

Answer 1

Here's a quick app that does what you want, in short you can define the countries as names for the vector code

library(shiny)
country <- c("Aruba","Afghanistan")
code <- c("ABW","AFG")
choices <- code
names(choices) <- country

ui <- fluidPage(
    selectInput(inputId = 'inSelect',
                label = "countries",
                choices = choices
                multiple = TRUE),
    textOutput("selected")
    
)

server <- function(input, output) {
    output$selected <- renderText({
        input$inSelect
    })
}

shinyApp(ui = ui, server = server)

For your purposes, for data.frame df use:

choices <- df$code
names(choices) <- df$country

This way the association between the two is defined as a single vector on app load, and you don't need to look up the codes in the table over and over (this answer is faster).