Fixed HLine dimension_values

holoviews/element/annotation.py

@@ -73,6 +73,15 @@ class HLine(Annotation):
     def __init__(self, y, **params):
         super(HLine, self).__init__(y, **params)
 
+    def dimension_values(self, dimension):
+        index = self.get_dimension_index(dimension)
+        if index == 0:
+            return []
+        elif index == 1:
+            return [self.data]
+        else:
+            return super(HLine, self).dimension_values(dimension)
+
 
 
 class Spline(Annotation):

tests/testannotations.py

@@ -0,0 +1,20 @@
+import numpy as np
+
+from holoviews import Image, HLine, VLine 
+from holoviews.element.comparison import ComparisonTestCase
+
+class AnnotationTests(ComparisonTestCase):
+    """
+    Tests allowable data formats when constructing
+    the basic Element types.
+    """
+
+    def test_hline_dimension_values(self):
+        hline = HLine(0)
+        self.assertEqual(hline.range(0), (None, None))
+        self.assertEqual(hline.range(1), (0, 0))
+
+    def test_vline_dimension_values(self):
+        hline = VLine(0)
+        self.assertEqual(hline.range(0), (0, 0))
+        self.assertEqual(hline.range(1), (None, None))