Shiny rhandsontable that is reactive to itself



am trying to create a shiny app that has a rhandsontable in it. I want rhandsontable to be able to update its values in one of its columns if the corresponding values in another column is selected/ checked. So far, I have been able to use reactive / observe events to change the output values between two objects but i am unable to wrap my head around it , i.e, how do i make once column of rhandsontable reactive to another column in the same table ?

Here is a simple example of what i am trying to build:


ui <- fluidPage(


server <- function(input,output,session)({

  data <- data.frame(c1=c(5,10,15), c2=c(3,6,9) , diff=c(0,0,0), select= as.logical( c(FALSE,FALSE,FALSE)))

  output$table <- renderRHandsontable({


shinyApp(ui = ui, server = server)

So if i check the column 'Select', column 'diff' should produce the difference between column c1 & c2