It’s a common requirement that your Shiny application should be bilingual. I have tried several methods and finally I got one which is not so difficult to maintain.

My idea is:

• Create a bilingual dictionary or a lookup table which contains three columns: value, English name and Norwegian name, like this one:

“` ruby value EN NO time Time Tid day Day Dag week Week Uke month Month Måned

“`

• Create a radio input with English and Norsk two options in file ui.R.

ruby radioButtons(inputId = "lang", label = "", choices = c("English" = "en", "Norsk" = "no"), selected = "English"),

• Create a function that converts value’s name to Norsk if user choose the Norsk radio.

“` ruby ## Bilingual lookup table; LANG <- unique(read.csv(“www/lang.csv”, sep = “;”, stringsAsFactors = FALSE)) E2N <- function(en, D = LANG) { for (i in 1:length(en)) { id <- which(D$value %in% en[i]) if (length(id) == 0) { id <- which(D$EN %in% en[i]) if (length(id) == 1) { en[i] <- ifelse(input$lang == “no”, D$NO[id], D$EN[id]) } else if (length(id) > 1) { print(“Mulit-variable matched!”) } } else if (length(id) == 1) { en[i] <- ifelse(input$lang == “no”, D$NO[id], D$EN[id]) } else if (length(id) > 1) { print(“Mulit-variable matched!”) } } return(en) }

“`

The ui.R file can be written as follow:

“` ruby shinyUI(pageWithSidebar( ## English or Norwegain? radioButtons(inputId = “lang”, label = “”, choices = c(“English” = “en”, “Norsk” = “no”), selected = “English”), # Select unit; sidebarPanel( uiOutput(“uiUnit”) ), mainPanel( h1(textOutput(“text1”)) ) ))

“`

In server.R file, we need load the E2N function first:

“` ruby shinyServer(function(input, output, session) { LANG <- data.frame(value = c(“time”, “day”, “week”, “month”), EN = c(“Time”, “Day”, “Week”, “Month”), NO = c(“Tid”, “Dag”, “Uke”, “Maaned”), stringsAsFactors = FALSE) observe({ E2N <- function(en, D = LANG) { for (i in 1:length(en)) { id <- which(D$value %in% en[i]) if (length(id) == 0) { id <- which(D$EN %in% en[i]) if (length(id) == 1) { en[i] <- ifelse(input$lang == “no”, D$NO[id], D$EN[id]) } else if (length(id) > 1) { print(“Mulit-variable matched!”) } } else if (length(id) == 1) { en[i] <- ifelse(input$lang == “no”, D$NO[id], D$EN[id]) } else if (length(id) > 1) { print(“Mulit-variable matched!”) } } return(en) } ## Input; output$uiUnit <- renderUI({ Items <- c(“day”, “week”, “month”) selectInput(inputId = “unit”, label = E2N(“time”), choices = E2N(Items), multiple = TRUE) }) ## Output; output$text1 <- renderText({ E2N(input$unit) }) }) })

“`

One shortcoming of this method is: when switching language, the application goes back to its original state. You can run above demo in R console:

“` ruby library(shiny) runGist(“https://gist.github.com/withr/3c01413b70b8a82706ab”)

“`