title: Add new row to dataframe, at specific row-index, not appended?
body: <p>The following code combines a vector with a dataframe:</p>
  
  <pre><code>newrow = c(1:4)
  existingDF = rbind(existingDF,newrow)
  </code></pre>
  
  <p>However this code always inserts the new row at the end of the dataframe.</p>
  
  <p>How can I insert the row at a specified point within the dataframe? For example, lets say the dataframe has 20 rows, how can I insert the new row between rows 10 and 11?</p>