ENH: Pass ndim through to DataobjImage

Author: effigies

nibabel/dataobj_images.py

@@ -28,8 +28,8 @@ def __init__(self, dataobj, header=None, extra=None, file_map=None):
         ----------
         dataobj : object
            Object containg image data.  It should be some object that retuns an
-           array from ``np.asanyarray``.  It should have a ``shape`` attribute
-           or property
+           array from ``np.asanyarray``.  It should have ``shape`` and ``ndim``
+           attributes or properties
         header : None or mapping or header instance, optional
            metadata for this image format
         extra : None or mapping, optional
@@ -392,6 +392,10 @@ def uncache(self):
     def shape(self):
         return self._dataobj.shape
 
+    @property
+    def ndim(self):
+        return self._dataobj.ndim
+
     @deprecate_with_version('get_shape method is deprecated.\n'
                             'Please use the ``img.shape`` property '
                             'instead.',