Customizing how DataTables displays missing values in Shiny [duplicate]

Question

DataTables, in Shiny, displays missing values as blank space. Is there a way to change that? I'm dreaming especially of the gray, italicized NAs that RStudio uses in its data viewer. I'd have no problem with injecting such strings into character columns for display purposes, but, of course, sometimes the columns are numeric, or date, and converting them just for display seems problematic.

MWE of DT's default missing values display:

library(DT)
library(shiny)

ui <- fluidPage(
    dataTableOutput("airquality")
)

server <- function(input, output) {
    output$airquality <- renderDataTable(airquality)
}

shinyApp(ui = ui, server = server)

Sheeran

Answer 1

You can do:

library(DT)

rowCallback <- c(
    "function(row, data){",
    "  for(var i=0; i<data.length; i++){",
    "    if(data[i] === null){",
    "      $('td:eq('+i+')', row).html('NA')",
    "        .css({'color': 'rgb(151,151,151)', 'font-style': 'italic'});",
    "    }",
    "  }",
    "}"  
  )

datatable(airquality, options = list(rowCallback = JS(rowCallback)))

Ovoviviparous

Perfect, thanks! I can see how this lets you apply any arbitrary CSS to just the missing values. – Sheeran

What to do to not display the rows containing NA/Missing values – Boult

This won't work if there are hidden columns, data[I] refer to the i-th col in the data while 'td:eq('+i+')' refers to the i-th visible column when displaying the DT first. – Kid

Good remark @moodymudskipper. That should work however if the hidden columns are at the end. – Forefinger

in part. but if they are themselves NA they won't be formatted once shown. – Kid

Answer 2

Customizing one of the options might be a good start:

options(htmlwidgets.TOJSON_ARGS = list(na = 'string'))

Here's the source so you can read the complete thread about this issue and its workarounds.

Donor

Thanks! That is something, though, looking at toJSON(), it looks like it can only give us unformatted "NA"s instead of blanks. – Sheeran