title: Numerical validation of a cell using rhandsontable R package
body: <p>I'd like to create a validation scheme when a table based on "rhandsontable" is updated. I have two columns: Min and Max and I'd like that when a cell in the column Max is updated, only it's allowed updating with a value greater than the previous column Min in the same row or vice-versa.  Maybe it's possible using hot_cols renderer and validating by means of subtraction greater than zero, etc. but I'm not familiar with "rhandsontable" or "hansontable" in general although I think this is possible, but I don't know how. Thanks. </p>
  
  <p>Toy example:</p>
  
  <pre><code>library(shiny)
  library(rhandsontable)
  
  if (interactive()) {
  
  ui &lt;- fluidPage(
     rHandsontableOutput('table'),
     tableOutput('table1')
  )
  
  server &lt;- function(input, output,session) {
  values &lt;- reactiveValues(df=data.frame(Parameter=c('A','B','C'),Min=c(10,20,30),Max=c(20,30,40)))
  observe({
    if(!is.null(input$table)){
      values$df &lt;- hot_to_r(input$table)
      output$table1&lt;-renderTable(values$df)
      }
  })
  output$table&lt;-renderRHandsontable({ 
    rhandsontable(values$df)%&gt;%
    hot_col("Parameter", readOnly = TRUE)%&gt;%
    hot_validate_numeric(col='Min', min = 1, max = 50,allowInvalid = FALSE)%&gt;%
    hot_validate_numeric(col='Max', min = 1, max = 50,allowInvalid = FALSE)
  })
  }
  shinyApp(ui, server)
  }
  </code></pre>