title: Calling Matlab function from python: "initializer must be a rectangular nested sequence"
body: <p>I am writing a python script from which I hope to call the Matlab anovan function. 
  I have attempted a basic test of this feature  on file <code>test.txt</code>, which contains 3 columns:</p>
  
  <pre><code>1.472008228227131532e+01 1.000000000000000000e+00 1.000000000000000000e+00
  1.423892587976163249e+01 2.000000000000000000e+00 1.000000000000000000e+00
  1.434051782779769013e+01 3.000000000000000000e+00 1.000000000000000000e+00
  1.478373164841650045e+01 4.000000000000000000e+00 1.000000000000000000e+00
  1.463143763527341612e+01 5.000000000000000000e+00 1.000000000000000000e+00
  1.580723346731706513e+01 6.000000000000000000e+00 1.000000000000000000e+00
  1.964295632547030124e+01 1.000000000000000000e+00 2.000000000000000000e+00
  1.922724696768608510e+01 2.000000000000000000e+00 2.000000000000000000e+00
  1.886686329445662480e+01 3.000000000000000000e+00 2.000000000000000000e+00
  1.960702674675711066e+01 4.000000000000000000e+00 2.000000000000000000e+00
  1.983434584140020007e+01 5.000000000000000000e+00 2.000000000000000000e+00
  2.050709640103466569e+01 6.000000000000000000e+00 2.000000000000000000e+00
  </code></pre>
  
  <p>This file is imported as array <code>data</code>.
  In matlab, the anovan function would be called as follows:</p>
  
  <pre><code>anovan(data(:,1),{data(:,2),data(:,3)})
  </code></pre>
  
  <p>In python, I have attempted to call the function like this:</p>
  
  <pre><code>import matlab.engine
  eng = matlab.engine.start_matlab() 
  data = np.genfromtxt('test.txt')
  eng.anovan(matlab.double(data[:,0]),matlab.int8(data[:,1:2]))
  </code></pre>
  
  <p>Unfortunately, this gives the following error:</p>
  
  <pre><code>ValueError: initializer must be a rectangular nested sequence
  </code></pre>
  
  <p>I can see that there is some issue in passing the last two array columns to the function, but am unsure of the solution. Any suggestions would be appreciated.   </p>