title: Realizing different column formats with numpy.savetxt
body: <p>I want to create a <code>.csv</code> file using <code>numpy.savetxt</code>. Each <code>row</code> of the file indicates a certain event. Every row has multiple <code>columns</code> indicating different elements of the event. The information stored in each <code>column</code> is different. Certain <code>columns</code> will contain single <code>float</code> values while others should contain two <code>floats</code> that are connected to each other. If I would call that column when loading the <code>.csv</code> I should obtain the two <code>float</code> values. </p>
  
  <p>I have the following code:</p>
  
  <pre><code>import numpy
  
  rows = 5
  columns = 2 
  save_values = numpy.zeros((rows, columns))
  
  for idx in xrange(rows):
    column_0 = float(idx)
    column_1 = [idx + 5., idx + 15.]
  
    save_values[idx, :] = column_0, column_1
  
  numpy.savetxt("outfile.csv", save_values, delimiter = ",")
  </code></pre>
  
  <p>This however results in the following error message: </p>
  
  <pre><code>  save_values[idx, :] = column_0, column_1
  ValueError: setting an array element with a sequence.
  </code></pre>
  
  <p>which is understandable. However, despite knowing why it is going wrong I am having a hard time realizing my goal.</p>
  
  <p>How can I achieve my goal?</p>