Get cell value next to clicked cell in Shiny DT

Question

My Shiny App renders DT frame in DT aka DataTables. I know how to get value of clicked cell by adding suffix:

_cell_clicked

For example:

print(unlist(( input$renderMpaDtOutput_cell_clicked  )))

returns named list object:

row   col value 
  1     9  3929

But I want to get cell value next to clicked cell (for example next to above coordinates: (row,col) = (1,9)).

Any ideas?

Answer 1

Just by adding coordinates to the row and col value, respectively. Take the table that was used to create the datatable, get input$dt_cell_clicked$row and $col and ask for table[input$dt_cell_clicked$row + 1, input$dt_cell_clicked$col] or vice versa. Example app:

library(shiny)

ui <- fluidPage(
 numericInput("x", "how many cells to the left/right?", min=-5, max=5, value=0),
 numericInput("y", "how many cells to the top/bottom?", min=-5, max=5, value=0),
 DT::dataTableOutput("dt"),
 uiOutput("headline"),
 verbatimTextOutput("shifted_cell")
)

server <- function(input, output) {

  output$headline <- renderUI({
    h3(paste0("You clicked value ", input$dt_cell_clicked$value, ". ", 
              input$x, " cells to the ", ifelse(input$x > 0, "right", "left"), " and ",
              input$y, " cells to the ", ifelse(input$y > 0, "bottom", "top"), " is:"))
  })
  # the value of the shifted cell
  output$shifted_cell <- renderPrint({
    mtcars[input$dt_cell_clicked$row + input$y, # clicked plus y to the bottom/top
           input$dt_cell_clicked$col + input$x] # clicked plus x to the left/right 
  })

  # the datatable
  output$dt <- DT::renderDataTable({
    DT::datatable(mtcars, select="none")})
}

shinyApp(ui, server)