ENH: Add ndim to ArrayProxy and DataobjImage

nibabel/arrayproxy.py

@@ -232,6 +232,10 @@ def header(self):
     def shape(self):
         return self._shape
 
+    @property
+    def ndim(self):
+        return len(self.shape)
+
     @property
     def dtype(self):
         return self._dtype

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.',

nibabel/ecat.py

@@ -680,6 +680,10 @@ def __init__(self, subheader):
     def shape(self):
         return self._shape
 
+    @property
+    def ndim(self):
+        return len(self.shape)
+
     @property
     def is_proxy(self):
         return True

nibabel/minc1.py

@@ -252,6 +252,10 @@ def __init__(self, minc_file):
     def shape(self):
         return self._shape
 
+    @property
+    def ndim(self):
+        return len(self.shape)
+
     @property
     def is_proxy(self):
         return True

nibabel/parrec.py

@@ -622,6 +622,10 @@ def __init__(self, file_like, header, mmap=True, scaling='dv'):
     def shape(self):
         return self._shape
 
+    @property
+    def ndim(self):
+        return len(self.shape)
+
     @property
     def dtype(self):
         return self._dtype

nibabel/tests/test_image_api.py

@@ -202,6 +202,7 @@ def validate_data_interface(self, imaker, params):
         # Check get data returns array, and caches
         img = imaker()
         assert_equal(img.shape, img.dataobj.shape)
+        assert_equal(img.ndim, len(img.shape))
         assert_data_similar(img.dataobj, params)
         for meth_name in self.meth_names:
             if params['is_proxy']:
@@ -210,6 +211,8 @@ def validate_data_interface(self, imaker, params):
                 self._check_array_interface(imaker, meth_name)
             # Data shape is same as image shape
             assert_equal(img.shape, getattr(img, meth_name)().shape)
+            # Data ndim is same as image ndim
+            assert_equal(img.ndim, getattr(img, meth_name)().ndim)
             # Values to get_data caching parameter must be 'fill' or
             # 'unchanged'
             assert_raises(ValueError, img.get_data, caching='something')
@@ -394,6 +397,17 @@ def validate_shape(self, imaker, params):
         # Read only
         assert_raises(AttributeError, setattr, img, 'shape', np.eye(4))
 
+    def validate_ndim(self, imaker, params):
+        # Validate shape
+        img = imaker()
+        # Same as expected ndim
+        assert_equal(img.ndim, len(params['shape']))
+        # Same as array ndim if passed
+        if 'data' in params:
+            assert_equal(img.ndim, params['data'].ndim)
+        # Read only
+        assert_raises(AttributeError, setattr, img, 'ndim', 5)
+
     def validate_shape_deprecated(self, imaker, params):
         # Check deprecated get_shape API
         img = imaker()

nibabel/tests/test_proxy_api.py

@@ -108,6 +108,14 @@ def validate_shape(self, pmaker, params):
         # Read only
         assert_raises(AttributeError, setattr, prox, 'shape', params['shape'])
 
+    def validate_ndim(self, pmaker, params):
+        # Check shape
+        prox, fio, hdr = pmaker()
+        assert_equal(prox.ndim, len(params['shape']))
+        # Read only
+        assert_raises(AttributeError, setattr, prox,
+                      'ndim', len(params['shape']))
+
     def validate_is_proxy(self, pmaker, params):
         # Check shape
         prox, fio, hdr = pmaker()