title: Numpy : convert 2D array to 3D array
body: <p>I have a <strong>2 dimensional array</strong> : <code>A = numpy.array([[1, 2, 3], [4, 5, 6]])</code> and would like to convert it to a <strong>3 dimensional array</strong> : <code>B = numpy.array([[[1, 2, 3], [4, 5, 6]]])</code></p>
  
  <p>Is there a simple way to do that ?</p>