Previous input in Shiny

Question

How to retain previous input in Shiny?

I want to show how estimates change according to user input.

E.g., If user changes input and an estimate is up, then i

Answer 1

You could store the previous and actual values inside a reactiveValues object:

rv$prev_bins is initialized as NULL, then on every value change, the new value is appended to the vector.

To keep only the previous and current values instead of all, use: rv$prev_bins <- c(tail(rv$prev_bins, 1), input$bins).

Code:

# Initialize reactive values
rv <- reactiveValues(prev_bins = NULL)

# Append new value to previous values when input$bins changes 
observeEvent(input$bins, {
  rv$prev_bins <- c(rv$prev_bins, input$bins)
})

# Output
output$print <- renderPrint({
  paste(rv$prev_bins, collapse = ",")
})

Output: