title: Keep only numeric in specific column in R?
body: <p>df</p>
  <pre><code>X1 X2 X3 X4 X5
  1 1 11 21 a k
  j 2 12 22 b l
  3 3 13 23 c m
  t 4 14 24 d n
  5 5 15 25 e o
  k 6 16 26 f p
  7 7 17 27 g q
  z 8 18 28 h r
  9 9 19 29 i s
  10 10 20 30 j 
  </code></pre>
  <p>I have a dataframe which contains 5 columns and 10 rows.  I want for only column 1 (X1) to keep only the numeric form and remove any characters eg character &quot;j&quot; in column X1, row 2.
  Might anyone know how to do this using a script in R?</p>
  <p>The final outcome would ideally look like this</p>
  <pre><code>   X1 X2 X3 X4 X5
  1   1 11 21  a  k
  3   3 13 23  c  m
  5   5 15 25  e  o
  7   7 17 27  g  q
  9   9 19 29  i  s
  10 10 20 30  j 
  </code></pre>