Shiny rhandsontable that is reactive to itself

Question

I 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:

library(shiny)
library(rhandsontable)

ui <- fluidPage(
  rHandsontableOutput('table')

)

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({
    rhandsontable(data)
  })


}) 

shinyApp(ui = ui, server = server)

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

Letsios Matthaios Letsios Matthaios · Accepted Answer · 2019-01-13T19:43:18

From what I understand, your goal is to do some calculation depending on the values of some other column. So if for example a box of the third column is checked, you might want to compute the difference between elements of column 1 and 2.

If you had just a data frame, that would be easy, wouldn't it? Well, this is possible using reactive values. The main idea is that you can store the rhandsontable in a data frame in the backend, modify the data frame and then render the modified data frame once again back in the handsontable.

I hope this helps:

For a more detailed example on reactive values you can see this: http://stla.github.io/stlapblog/posts/shiny_editTable.html and this : https://www.youtube.com/watch?v=BzE1JmC0F6Q&list=PL6wLL_RojB5wXR3NR3K38sIvexZ_45alY&index=3

library(rhandsontable)
library(shiny)


ui <- fluidPage(
  mainPanel(
    rHandsontableOutput("hot")
  )
)

server = function(input, output, session){

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

  observe({
    if(!is.null(input$hot)){
      values$data <- as.data.frame(hot_to_r(input$hot))
      isolate(values$data[,'diff'] <- ifelse(values$data[,'select'], values$data[,'c1']-values$data[,'c2'] ,0))
      print(values$data)
      output$hot <- renderRHandsontable({
        rhandsontable(values$data)
      })
    }
  })    

  output$hot <- renderRHandsontable({
    rhandsontable(values$data)
  })

}

shinyApp(ui, server)

Shiny rhandsontable that is reactive to itself

1 Answers