title: Repeat rows of a data.frame N times
body: <p>I have the following data frame:</p>
  <pre><code>data.frame(a = c(1,2,3),b = c(1,2,3))
    a b
  1 1 1
  2 2 2
  3 3 3
  </code></pre>
  <p>I want to repeat the rows <em>n</em> times. For example, here the rows are repeated 3 times:</p>
  <pre><code>  a b
  1 1 1
  2 2 2
  3 3 3
  4 1 1
  5 2 2
  6 3 3
  7 1 1
  8 2 2
  9 3 3
  </code></pre>
  <p>Is there an easy function to do this in R? Thanks!</p>