title: Aggregate Inserting Strings
body: <p>I have a Dataframe called teachers:</p>
  
  <pre><code>Teachers &lt;- data.frame(Discipline = c("Math","Math","Chem","Arts","History","History"),
                         Teacher = c("Mark","Mark","Peter","Richard","Mark","Mark"),
                         Position  = c("Coord","Teacher", "Teacher", "Teacher","Coord","Teacher"))
  </code></pre>
  
  <p>In this case Mark is Coord/Teacher in two disciplines. How can I, using basic R commands, get an output like this:</p>
  
  <pre><code>Teachers2 &lt;- data.frame(Discipline = c("Math","Chem","Arts","History"),
                          Teacher = c("Mark","Peter","Richard","Mark"),
                          Position  = c("Coord/Teacher", "Teacher", "Teacher","Coord/Teacher"))
  </code></pre>
  
  <p>I did a similar grouping with some help at <a href="https://stackoverflow.com/questions/46534419/grouping-inserting-strings">Grouping inserting strings</a></p>
  
  <p>Thanks for your Help</p>