R Shiny App: Reactive/Calculate column in Rhandsontable

Question

I am using Rhansontable package, i want to create a table where if i change value in one column then another column automatically calculate. For example:

DF = data.frame(num = 1:10, price = 1:10,stringsAsFactors = FALSE)

In above dataframe another column "Total" (num*price) should calculate automatically when i change the value in column "num"

Can please help with sample shiny code?

Answer 1

I think this is what you want

#rm(list = ls())
library(shiny)
library(rhandsontable)

## Create the dataset
DF = data.frame(num = 1:10, price = 1:10,Total = 1:10,stringsAsFactors = FALSE)
numberofrows <- nrow(DF)

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

  # Initiate your table
  previous <- reactive({DF})

  MyChanges <- reactive({
    if(is.null(input$hotable1)){return(previous())}
    else if(!identical(previous(),input$hotable1)){
      # hot.to.df function will convert your updated table into the dataframe
      mytable <- as.data.frame(hot_to_r(input$hotable1))
      # here the second column is a function of the first and it will be multipled by 100 given the values in the first column
      mytable <- mytable[1:numberofrows,]

      # Add some test cases
      mytable[,1][is.na(mytable[,1])] <- 1
      mytable[,2][is.na(mytable[,2])] <- 1
      mytable[,3] <- mytable[,1]*mytable[,2]
      mytable
    }
  })
  output$hotable1 <- renderRHandsontable({rhandsontable(MyChanges())})
})

ui <- basicPage(mainPanel(rHandsontableOutput("hotable1")))
shinyApp(ui, server)