How can I concatenate non-reactive values with reactive value for a graph title? R Shiny

Question

I am having trouble naming a graph title that contains a normal string AND reactive value/s.

I'm trying to do something like this: main = "Examination of: " + input$userInput

The error message is: non-numeric argument to binary operator. Does anyone know how to fix this?

Answer 1

The below code could give you what you needed.

library(shiny)
ui <- basicPage(
  uiOutput("test"),
  plotOutput("plot1")
)
server <- function(input, output) {
  output$test <- renderUI({
    selectInput("dummy", "Select one value", c(mtcars$qsec))
  })
  output$plot1 <- renderPlot({
    plot(mtcars$wt, mtcars$mpg, main = paste0("this is main ",input$dummy,""))
  })
}
shinyApp(ui, server)

The usage of selectInput is for testing your requirement. Make the needful changes for your actual problem.