title: R Shiny DataTables: Format numbers not by column but by row
body: <p>My data is a matrix like this:</p>
  
  <pre><code>             Buy and Hold              Strategy
  [1,]    1.0000000000000000   19.0000000000000000
  [2,]   -0.6300786023496699   -0.2361973739022651
  [3,]   -0.0872213557701079   -0.0244237977843418
  [4,]   -0.3461103323781194   -0.1010012410191289
  [5,]    0.0000000000000000    0.4949083503054990
  [6,]    0.2520044841505053    0.2418168087629348
  [7,]   -0.7946470924762163   -0.7731378277502762
  [8,] 1864.0000000000000000 1707.0000000000000000
  </code></pre>
  
  <p>As you see I need a formatting by row and not by column. For example [1,] should be without decimals, so there is a 1 and a 19. However Rows [2,]-Row[7,] should be a percentage like xx.x% and Row[8,] again a number without decimals. How can I achieve that? I have no clue how to use these callback functions and I assume there lies the solution..</p>