Add label to sparkline plot in datatable

Is it possible to add a custom label to a sparkline plot?

For example, in the code below, I would like to label each bar with the corresponding letter in the label column.

Building from a previous [answer]

require(sparkline)
require(DT)
require(shiny)
require(tibble)

# create data


spark_data1<-tribble(
  ~id,  ~label,~spark,
  "a", c("C,D,E"),c("1,2,3"),
  "b", c("C,D,E"),c("3,2,1")
)

ui <- fluidPage(
  sparklineOutput("test_spark"),
  DT::dataTableOutput("tbl")
)

server <- function(input, output) {

  output$tbl <- DT::renderDataTable({
    line_string <- "type: 'bar'"
    cd <- list(list(targets = 2, render = JS("function(data, type, full){ return '<span class=sparkSamples>' + data + '</span>' }")))
    cb = JS(paste0("function (oSettings, json) {\n  $('.sparkSamples:not(:has(canvas))').sparkline('html', { ", 
                   line_string, " });\n}"), collapse = "")
    dt <-  DT::datatable(as.data.frame(spark_data1),  rownames = FALSE, options = list(columnDefs = cd,fnDrawCallback = cb))

  })

}

shinyApp(ui = ui, server = server)