CODEWITHSUNDEEP
rshiny
kluu
kluu

Reputation: 2995

Shiny: create a reactiveValues from a list of names

Is it possible to generate a reactiveValues where the variable names are given by a certain list list_of_names? These variables could for example store a boolean indicating the state of the corresponding variable.

Imagine I have a list x:

x <- lapply(LETTERS, function(i) TRUE)
names(x) <- LETTERS

Can I generate a reactiveValues rv from x that behaves like x?

I haven't been to able to do so, and all I could came up with was something like this:

ui <- fluidPage(
  textOutput("boolean")  
)

server = function(input, output, session){
  nms <- LETTERS[1:10]

  ### lines that I would change
  rv <- reactiveValues(A = TRUE)
  for (n in nms) {rv[[n]] <- TRUE}
  ###

  output$boolean <- renderText(rv[["D"]])
}

shinyApp(ui,server)

It works, but I'm sure there must be a simpler and "cleaner" way to do this, as x and rv are quite similar. Thanks to anyone that can help me on this one.

Upvotes: 5

Views: 2026

Answers (1)

L&#233;on Ipdjian
L&#233;on Ipdjian

Reputation: 818

A simple way to do it is to call your vector as arguments of the function reactiveValues :

ui <- fluidPage(
  textOutput("boolean")  
)

server = function(input, output, session){
  x <- as.list(rep(T,10))
  names(x) <- LETTERS[1:10]
  
  # x as arguments of reactiveValues function
  rv <- do.call("reactiveValues",x)
  
  # still works
  output$boolean <- renderText(rv[["D"]])
}

shinyApp(ui,server)

EDIT : to me, it is not possible to maintain the original order of the vector. An other way is to keep it somewhere else (if possible), then to call it whenever needed :

ui <- fluidPage(
  textOutput("boolean")  
)

server = function(input, output, session){
  x <- as.list(rep(T,10))
  names(x) <- rev(LETTERS[1:10])
  true_order <- levels(factor(names(x),names(x)))
  
  # x as arguments of reactiveValues function
  rv <- do.call("reactiveValues",x)
  
  # still works
  output$boolean <- renderText({
    p <- names(x)
    paste0(p[sapply(true_order,function(x,p){which(p == x)},p=p)], collapse = "-")
  }
  )
}

Upvotes: 7

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