title: Append data to existing pytables table
body: <p>I am new to PyTables and implemented a few basic techniques of inserting and retrieving data from a table in Pytables. However, I am not sure about how to insert data in an existing table of PyTables because all I read/get in the <a href="http://pytables.github.io/usersguide/tutorials.html#creating-a-pytables-file-from-scratch" rel="nofollow noreferrer">tutorial</a> is creating a new table (using <code>h5file.createTable()</code> method). Here is the basic code that tutorial has about inserting data into PytTables table created from scratch:</p>
  
  <pre><code>h5file = openFile("tutorial1.h5", mode = "w", title = "Test file")
  group = h5file.createGroup("/", 'detector', 'Detector information')
  table = h5file.createTable(group, 'readout', Particle, "Readout example")
  
  for i in xrange(10):
      particle['name']  = 'Particle: %6d' % (i)
      particle['TDCcount'] = i % 256
      particle['ADCcount'] = (i * 256) % (1 &lt;&lt; 16)
      particle['grid_i'] = i
      particle['grid_j'] = 10 - i
      particle['pressure'] = float(i*i)
      particle['energy'] = float(particle['pressure'] ** 4)
      particle['idnumber'] = i * (2 ** 34)
      # Insert a new particle record
      particle.append()
  
      table.flush()
  </code></pre>
  
  <p>P.S. There is one <a href="http://pytables.github.io/usersguide/tutorials.html#appending-data-to-an-existing-table" rel="nofollow noreferrer">place</a> in this tutorial that talks about appending data to an existing table, but uses the table that was created from scratch and basically gives no idea about selecting pre-existing table for appending data. Kindly help. Thanks.</p>