title: Add comma to numbers every three digits in datatable (R)
body: <p>Suppose my data looks like this:</p>
  
  <pre><code>df1 = data.frame(A=c(1000000.51,5000.33), B=c(0.565,0.794))
  </code></pre>
  
  <p>I want to use <a href="http://rstudio.github.io/DT/" rel="noreferrer">DataTables </a> and have column A be (1,000,001 ; 5,000)</p>
  
  <pre><code>library(DT)
  datatable(df1)  %&gt;%  formatPercentage('B', 2) %&gt;%
    formatRound('A',digits = 0)
  </code></pre>
  
  <p>I know i can use scales</p>
  
  <pre><code>library(scales)    
  comma_format()(1000000)
  </code></pre>
  
  <p>but I'm not sure how to combine that with DataTables </p>
  
  <p>Thanks!</p>