title: How to create numpy structured array with multiple fields of different shape?
body: <p>I'm new to working with numpy arrays and I'm having trouble creating a structured array.  I'd like to create something similar to a Matlab structure where the fields can be arrays of different shapes.</p>
  
  <pre><code>a=numpy.array([1, 2, 3, 4, 5, 6,]);
  b=numpy.array([7,8,9]);
  c=numpy.array([10,11,12,13,14,15,16,17,18,19,20]);
  
  ##Doesn't do what I want
  data=numpy.array([a, b, c],dtype=[('a','f8'),('b','f8'),('c','f8')]);  
  </code></pre>
  
  <p>I'd like <code>data['a']</code> to return matrix a, <code>data['b']</code> to return matrix b, etc.  When reading in a Matlab structure, the data is saved in this format so I know it must be possible.</p>