title: Set type for fromarray() in opencv for python
body: <p>I am using Python 2.7 and opencv 2.1.</p>
  
  <p>I have a numpy array and I want to convert it to an opencv matrix of type "cv.CV_32FC1".
  How can I set the type ?</p>
  
  <p>"CreateMat()" allows for explicit type setting but "fromarray()" doesnt.
  If I just apply fromarray on a float array the type check fails (one of the next modules performs a specific type check for CV_32FC1) </p>
  
  <p>thanks !</p>