title: R: Adding NAs into Data Frame
body: <p>I have a data frame like so:</p>
  
  <pre><code>Name   Position   Value
  a         1        0.2
  a         3        0.4
  a         4        0.3
  b         1        0.5
  b         2        0.4
  b         5        0.3
  c         2        0.3
  c         3        0.4
  c         5        0.1
  d         1        0.2
  d         2        0.4
  d         3        0.5
  </code></pre>
  
  <p>I want to make it so that Position always go from 1 to 5 for each Name and fill in NAs into Value like so:</p>
  
  <pre><code>Name   Position   Value
  a         1        0.2
  a         2        NA
  a         3        0.4
  a         4        0.3
  a         5        NA
  b         1        0.5
  b         2        0.4
  b         3        NA
  b         4        NA
  b         5        0.3
  c         1        NA
  c         2        0.3
  c         3        0.4
  c         4        NA
  c         5        0.1
  d         1        0.2
  d         2        0.4
  d         3        0.5
  d         4        NA
  d         5        NA
  </code></pre>
  
  <p>Is there a way to do it without creating a dummy data frame with the first 2 columns then doing some sort of outer join with merge?</p>
  
  <p>Thanks.</p>