use variable in UI of R Shiny? - r

Question

I have created quite a large app that I now want to extent by introducing tabs. So far I have, as an example:
ui.R
shinyUI(
#OLD CODE
)
server.R
(
#OLD CODE
)
What I would like to do:
ui.R
shinyUI(
tabsetPanel(
"Tabs",
tabPanel("Old Code",value="tb1"),
tabPanel("New Code",value="tb2"),
id = "nlp"
),
if (id=="tb1") {
#OLD CODE
} else if (id=="tb2") {
#New Code
} else {
#Do nothing
}
How do I get the if function to recognise id as a variable?
When I run the script it comes up with the error object 'id' not found. So then I've tried input$id and output$id with no avail.
I have also tried going to the server.R and tried
Server.R
output$id <- renderText("id")
also didn't work when trying to bring that back into the UI
and I have also tried
Server.R
output$id <- reactive({input$id})
this also didn't work when I tried to use it in the UI. Where am I going wrong and how can I use the Id variable in the UI?
Thanks

Answer 1

Based on the Shiny Tabsets example, you should be putting the UI elements into each call to tabPanel, like so:
shinyUI(
tabsetPanel(
tabPanel(
title = "Old Code",
plotOutput('plot1'),
plotOutput('plot2')
),
tabPanel(
title = "New Code",
tableOutput('table')
),
id = "nlp"
)
)
Unless you are trying to do more than necessary, your code does not need to know what tab the client has selected. I may be wrong (please do not think I'm an authority on shiny), I think the elements within the not-selected tabs are not unnecessarily recalculated (unless dependencies exist and require it).