title: How do I get a contingency table?
body: <p>I am trying to create a contingency table from a particular type of data. This would be doable with loops etc... but because my final table would contain more than 10E5 cells, I am looking for a pre-existing function.</p>
  
  <p>My initial data are as follow:</p>
  
  <pre><code>PLANT                  ANIMAL                          INTERACTIONS
  ---------------------- ------------------------------- ------------
  Tragopogon_pratensis   Propylea_quatuordecimpunctata         1
  Anthriscus_sylvestris  Rhagonycha_nigriventris               3
  Anthriscus_sylvestris  Sarcophaga_carnaria                   2
  Heracleum_sphondylium  Sarcophaga_carnaria                   1
  Anthriscus_sylvestris  Sarcophaga_variegata                  4
  Anthriscus_sylvestris  Sphaerophoria_interrupta_Gruppe       3
  Cerastium_holosteoides Sphaerophoria_interrupta_Gruppe       1
  </code></pre>
  
  <p>I would like to create a table like this:</p>
  
  <pre><code>                       Propylea_quatuordecimpunctata Rhagonycha_nigriventris Sarcophaga_carnaria Sarcophaga_variegata Sphaerophoria_interrupta_Gruppe
  ---------------------- ----------------------------- ----------------------- ------------------- -------------------- -------------------------------
  Tragopogon_pratensis   1                             0                       0                   0                    0
  Anthriscus_sylvestris  0                             3                       2                   4                    3
  Heracleum_sphondylium  0                             0                       1                   0                    0
  Cerastium_holosteoides 0                             0                       0                   0                    1
  </code></pre>
  
  <p>That is, all plant species in row, all animal species in columns, and sometimes there are no interactions (while my initial data only list interactions that occur).</p>