Demo of DT::datatable column indexing

demo_DT

# libraries
library(tidyverse)
library(DT)

set.seed(1234)

# generate data
dat <- tibble(
  A = runif(5, 0, 1),
  B = runif(5, 0, 1), 
  C = runif(5, 0, 1), 
)

# initial table with no formatting
DT::datatable(dat,rownames = FALSE)

# formatted table 
# use columnDefs to center columns; columns are indexed at 0
# use formatRound to round values; columns are indexed at 1
DT::datatable(dat,
              rownames = FALSE,
              options = list(columnDefs = list(
                list(className = 'dt-center',
                     targets = 0:2)
              )))  %>%
  DT::formatRound(1:3, 2)