CODEWITHSUNDEEP
rshinyreactive
Elie Ker Arno
Elie Ker Arno

Reputation: 346

How to get a reactive data.frame in a shiny application

I wonder how I could get my shiny app react to any modification brought to a data.frame. This can be useful in many ways. Something like:

[server part]
rv <- reactiveValues(
  df <- data.frame(...)
)

observeEvent(rv$df, {
  ...
})

Upvotes: 0

Views: 1038

Answers (1)

Elie Ker Arno
Elie Ker Arno

Reputation: 346

Here is an example of a soluce I came up with. Please note that this is only one use case (without modules). I'll let you know that I successfully adapted it on a more complex app (> 100 inputs). Technical details are included into the code as comments.

library(shiny)

# Simple GUI to let the user play with the app.
ui <- fluidPage(
  actionButton("dev","dev"),
  actionButton("dev2","dev2")
)

# Here comes the serious business
server <- function(input, output, session) {
  # First, I use reactiveValues (clear way to store values)
  rv <- reactiveValues(
    # And here is our main data frame
    df = data.frame(a = 0, b = 1)  
  )
 
  # Ok, let's get the magic begin ! R recognizes this in the current environment:
  makeReactiveBinding("rv$df")
  # Also works with things such as:
  #  makeReactiveBinding(sprint("rv$%s", "df"))
  # which opens the way to dynamic UI. 
  
  # Then, I get a way to catch my table from a reactive
  rdf <- reactive(rv$df)

  # And there, I only have to call for this reactive to get data.frame-related event
  observe(print(rdf()$b))

  # Here are some little ways to interact with the app
  # Notice the `<<-` assignment to store new values
  # Add values to df$a (expected behavior: print df$b at its value)
  observeEvent(input$dev, {
    rv$df$a <<- rv$df$a+1
  })
  # Add values to df$b (expected behavior: print df$b at its new value)
  observeEvent(input$dev2, {
      rv$df$b <<- rv$df$b+1
  })
}

shinyApp(ui, server)

I hope this might help some users of Shiny. I find this quite easy and quick to implement and really useful.

Upvotes: 2

Related Questions