def __init__(self, parents=None, affine=np.eye(4), shape=None,
xyz=None, id='nroi'):
"""
Building the NROI
Parameters
----------
parents=None: array of shape(k) providing
the hierachical structure
if parent==None, None is returned
affine=np.eye(4), array of shape(4,4),
coordinate-defining affine transformation
shape=None, tuple of length 3 defining the size of the grid
implicit to the discrete ROI definition
xyz=None, list of arrays of shape (3, nvox)
that yield the grid position of each grid guy.
id='nroi', string, region identifier
"""
if parents==None:
return None
k = np.size(parents)
Forest.__init__(self,k,parents)
MultipleROI.__init__(self,id, k, affine, shape, xyz)
