ENH: Add a useful __repr__ for itkMatrix

Author: HastingsGreer

Wrapping/Generators/Python/PyBase/pyBase.i

@@ -554,6 +554,13 @@ str = str
                 vnl_reference = self.__GetVnlMatrix_orig__()
                 vnl_copy = type(vnl_reference)(vnl_reference)
                 return vnl_copy
+            def __repr__(self):
+                vnl_mat = self.GetVnlMatrix()
+                python_list_mat = [
+                  [vnl_mat.get(i, j) for j in range(vnl_mat.cols())]
+                  for i in range(vnl_mat.rows())
+                ]
+                return repr(type(self)).split("'")[1] + "(" + repr(python_list_mat) + ")"
             %}
         }
 

Wrapping/Generators/Python/Tests/extras.py

@@ -395,6 +395,8 @@ def custom_callback(name, progress):
 assert arr2[0, 0] == 2
 # and make sure that the matrix hasn't changed.
 assert m_itk(0, 0) == 1
+# Test __repr__
+assert repr(m_itk) == "itk.itkMatrixPython.itkMatrixD33([[1.0, 0.0, 0.0], [0.0, 1.0, 0.0], [0.0, 0.0, 1.0]])"
 
 # test .astype for itk.Image
 numpyImage = np.random.randint(0, 256, (8, 12, 5)).astype(np.uint8)