more tests on rolling views

skimage/util/array_views.py

@@ -209,9 +209,12 @@ def rolling_view(arr, window_shape):
     """
 
     # -- basic requirements on inputs
-    assert isinstance(arr, np.ndarray)
-    assert isinstance(window_shape, tuple)
-    assert len(window_shape) == arr.ndim
+    if not isinstance(arr, np.ndarray):
+        raise ValueError('the input should be an ndarray object')
+    if not isinstance(window_shape, tuple):
+        raise ValueError('the window shape should be a tuple')
+    if not (len(window_shape) == arr.ndim):
+        raise ValueError('array dimension and window length dont match')
 
     # -- input array dimension
     N = arr.ndim

skimage/util/tests/test_array_views.py

@@ -1,7 +1,7 @@
 import numpy as np
 from nose.tools import raises
 from numpy.testing import assert_equal
-from skimage.util.array_views import block_view
+from skimage.util.array_views import block_view, rolling_view
 
 
 @raises(ValueError)
@@ -65,3 +65,77 @@ def test_block_view_3D_array():
                                           [58, 59]]],
                                         [[[76, 77],
                                           [82, 83]]]]))
+
+
+@raises(ValueError)
+def test_rolling_view_input_not_array():
+
+    A = [1, 2, 3, 4, 5]
+    rolling_view(A, (2,))
+
+
+@raises(ValueError)
+def test_rolling_view_window_not_tuple():
+
+    A = np.arange(10)
+    rolling_view(A, [2])
+
+
+@raises(ValueError)
+def test_rolling_view_wrong_window_dimension():
+
+    A = np.arange(10)
+    rolling_view(A, (2,2))
+
+
+@raises(ValueError)
+def test_rolling_view_negative_window_length():
+
+    A = np.arange(10)
+    rolling_view(A, (-1,))
+
+
+@raises(ValueError)
+def test_rolling_view_window_too_large():
+
+    A = np.arange(10)
+    rolling_view(A, (11,))
+
+
+def test_rolling_view_1D():
+
+    A = np.arange(10)
+    window_shape = (3,)
+    B = rolling_view(A, window_shape)
+    assert_equal(B, np.array([[0, 1, 2],
+                              [1, 2, 3],
+                              [2, 3, 4],
+                              [3, 4, 5],
+                              [4, 5, 6],
+                              [5, 6, 7],
+                              [6, 7, 8],
+                              [7, 8, 9]]))
+
+
+def test_rolling_view_2D():
+
+    A = np.arange(5*4).reshape(5, 4)
+    window_shape = (4, 3)
+    B = rolling_view(A, window_shape)
+    assert_equal(B.shape, (2, 2, 4, 3))
+    assert_equal(B, np.array([[[[ 0,  1,  2],
+                                [ 4,  5,  6],
+                                [ 8,  9, 10],
+                                [12, 13, 14]],
+                               [[ 1,  2,  3],
+                                [ 5,  6,  7],
+                                [ 9, 10, 11],
+                                [13, 14, 15]]],
+                              [[[ 4,  5,  6],
+                                [ 8,  9, 10],
+                                [12, 13, 14],
+                                [16, 17, 18]],
+                               [[ 5,  6,  7],
+                                [ 9, 10, 11],
+                                [13, 14, 15],
+                                [17, 18, 19]]]]))