Dynamically Resizing a ggplot2 Graph in R Shiny

Question

I have tried this:

output$plot <- renderPlot({
  getPlot()
}, width=input$plotX, height=input$plotY) # referring to two numericInput boxes

But I get this error:

Error in .getReactiveEnvironment()$currentContext() : Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)

The help text suggests that I use functions, and that within those functions I can refer to reactive values, etc. But having done something like that, I still get the same error...

Is there a way to allow users to resize the plot based on values they enter into the app?

Answer 1

You can wrap a reactive value into a function using shiny:::exprToFunction.

For example,

output$plot <- renderPlot({
  getPlot()
}, width=exprToFunction(input$plotX), 
   height=exprToFunction(input$plotY)))

should do the trick.