Shiny DT slice date/time values

[Scott Goley]

Using the following script, I'm trying to cut the time values down to just HH:MM values. I noticed that DataTables originally in JS has the slice() method available for this kind of selection. However, so far I've been unable to implement this through functions / options currently available through DT including the params mentioned here. 

library(shiny)
library(DT)
library(dplyr)
library(magrittr)


 
  # server-side processing
 
  base<-as.POSIXct('2000-01-01 00:00:00 EST')
 
  mtcars2 = mtcars[, 5:6]
  mtcars2 %<>%
    mutate(drat = base+(3600*drat),
           wt = base+(3600*wt))
   
    DT::datatable(mtcars2,
        extensions = 'Buttons',
        options = list(
          scrollX = TRUE,
          scrollY = TRUE,
          pageLength = 10,
          dom = 'Blfrtip',
          buttons = c('copy', 'csv', 'excel', 'pdf', 'print')
        )
  ) %>%
  formatDate( 1:2,method = 'toLocaleTimeString', params = list('en-US',hour = 'numeric', hour12 = 'true', minute = 'numeric'))

Final rows would have the format HH:MM for all values and drop seconds, AM/PM, and TZ. 

Thanks!

[Greg L]

There are 2 minor issues with your formatDate params:

- options should be in an object/list by themselves (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toLocaleTimeString)

- the JSON serializer in DT uses R's built-in TRUE/FALSE logicals, not 'true' / 'false' strings

formatDate(1:2, method = 'toLocaleTimeString',
           params = list('en-US', list(hour = 'numeric', minute = 'numeric', hour12 = FALSE)))

Btw, that DataTable slice looks like it clones the DataTable, probably not what you were thinking

[Scott Goley]

Yes, sorry - that must have been from a copy / paste from one of my older versions but I am using R logicals and I do have the param options in a sub list. 

Can you confirm that even with those options specified, it still populates seconds, AM/PM, and Time Zone?

And yes, slice from DataTables isn't what I meant exactly. Something more like String.prototype.slice(). 

Thanks Greg. 

[Greg L]

Are you running this in RStudio or a Shiny app? I just realized the RStudio Viewer (at least mine, v1.0.136) doesn't support toLocaleTimeString's locale or options arguments. Works fine in Chrome though.

If it's not supported where you're running this, then you could fall back to something like String.prototype.slice(). See the DataTables docs for how to use columns.render.

DT::datatable(mtcars2,
              extensions = 'Buttons',
              options = list(
                scrollX = TRUE,
                scrollY = TRUE,
                pageLength = 10,
                dom = 'Blfrtip',

                buttons = c('copy', 'csv', 'excel', 'pdf', 'print'),
                columnDefs = list(
                  list(targets = c(1, 2), render = JS("
                    function(data) {
                      return data.slice(-9, -4);
                    }"))
                )
              )
)