title: Concatenate several tables in R
body: <p>I have 5 <code>data.frames</code> with 10 rows, which correspond to 10 politicians.
  I use <code>table()</code> to count all the political groups in each <code>data.frame</code>.</p>
  
  <p>So I get 10 tables like this :</p>
  
  <pre><code>grpol.1 &lt;- table(df1$group_pol)
  grpol.1
    NI RRDP  SRC  UDI  UMP 
    1    2   3    3    1 
  grpol.2
    RRDP  UDI  ECOLO 
    5       4      1 
  </code></pre>
  
  <p>Now, I would like to concatenate (by column) all of these tables into just one <code>data.frame</code>. There are 7 political groups in all.
  <em>Note</em> all these tables do not have the same number of columns. </p>
  
  <p>I would like to obtain something like:</p>
  
  <pre><code> group_pol  grpol.1  grpol.2  ... grpol.5
  1 NI              1        0
  2 RRDP            2        5
  3 SRC             3        0
  4 UDI             3        4 
  5 UMP             1        0
  6 GDR             0        0
  7 ECOLO           0        1
  </code></pre>
  
  <p>Normally, in this case, I would use merging. However it seems impossible to convert tables to <code>data.frame</code>s in order to merge.
  So, what is the alternative to concatenate tables which do not have similar columns ?</p>
  
  <p>Thanks for help,</p>