Dynamically add elements with ActionButton in a Shiny app

[Johanna]

I'm trying to write an app where one can throw a coin several times, so every time the ActionButton is pressed a new element is added to a vector. This vector then I would like to use to display the results in a plot.
My problem is that vector. I don't yet have lots of experience with Shiny, so I don't know if there's a specific function for that as I didn't find anything since now.

Can someone give me a hint of how that would be possible?
Thanks in advance!

[nirgrahamuk]

you want to add a value to a vector ? Thats the c() concatenation function

(v1 <- 1:3)
#1 2 3
(v2 <- c(v1, 4))
#1 2 3 4

[Johanna]

Yes, I know that function. But it didn't work in Shiny. I always got the Error "Error in: evaluation nested too deeply: infinite recursion / options (expressions =)?"
I think the problem is that I want to do that in a Shiny App. So I would need a vector where a value is added every time the person is pressing the ActionButton.

[nirgrahamuk]

library(shiny)

ui <- fluidPage(
  actionButton("b1", "press"),
  tableOutput("t1")
)

server <- function(input, output, session) {
  hist_vec <- reactiveVal(NULL)

  observeEvent(input$b1, {
    hist_vec(c(
      hist_vec(),
      sample(c("H", "T"), 1)
    ))
  })

  output$t1 <- renderTable({
    r <- req(hist_vec())
    as.data.frame(table(r))
  })
}

shinyApp(ui, server)

[Johanna]

Thank you very much!!!