title: R distance matrix format from already calculated data
body: <p>This is  my first time working with R. </p>
  
  <p>I have a table with 3 columns and 12090 rows (156 bacteria). The first two columns are names of bacteria and the last column is a number indicating relatedness between the organisms (based on a kind of genome similarity). example would be (made up numbers):</p>
  
  <pre><code>bacteria1    bacteria2    0.25846
  bacteria1    bacteria3    0.35986
  bacteria2    bacteria1    0.57896
  bacteria2    bacteria3    0.54596
  bacteria3    bacteria1    0.23659
  bacteria3    bacteria2    0.36528
  </code></pre>
  
  <p>I would like to be able to neighbor join these into a phylogenetic tree of sorts. I see that 'nj' needs a distance matrix to do this. How would I convert this into a distance matrix or usable format? (The numbers are already distance so there shouldn't be any math being done)
  I've tried as.dist() and as.matrix() and reshape() but being new I may have done everything wrong. (reshape may be what I need..)</p>
  
  <p>Or if anyone knows how to make these into a tree through other means that would be grand.</p>
  
  <p>Thanks for any help. </p>