R Shiny: keep old output

Question

In a Shiny app, is there a way to keep old reactive output and display it in the app along with new reactive output? To provide an example: say I want to display the summary

Answer 1

Here's an approach that works. It uses a reactiveValues object, and each time you click the "Fit Model" button, it appends the new model to the end of the list. The numeric input controls how many models to display on the screen. This preserves every model you fit in the session.

I didn't do the stargazer table because I'm not that familiar with it. But you should be able to adapt this pretty easily.

library(shiny)
library(broom)

shinyApp(
  ui = 
    shinyUI(
      fluidPage(
        sidebarLayout(
          sidebarPanel(
            checkboxGroupInput(inputId = "indep",
                               label = "Independent Variables",
                               choices = names(mtcars)[-1],
                               selected = NULL),
            actionButton(inputId = "fit_model",
                         label = "Fit Model"),
            numericInput(inputId = "model_to_show",
                         label = "Show N most recent models",
                         value = 2)
          ),
          mainPanel(
            htmlOutput("model_record")
          )
        )
      )
    ),

  server = 
    shinyServer(function(input, output, session){
      Model <- reactiveValues(
        Record = list()
      )

      observeEvent(
        input[["fit_model"]],
        {
          fit <- 
            lm(mpg ~ ., 
               data = mtcars[c("mpg", input[["indep"]])])

          Model$Record <- c(Model$Record, list(fit))
        }
      )

      output$model_record <- 
        renderText({
          tail(Model$Record, input[["model_to_show"]]) %>%
            lapply(tidy) %>%
            lapply(knitr::kable,
                   format = "html") %>%
            lapply(as.character) %>%
            unlist() %>%
            paste0(collapse = "<br/><br/>")
        })

    })
)