Allow to use different function or precision for 'approx equals'. (#2179

)

holoviews/element/comparison.py

@@ -17,6 +17,7 @@
 thus would not supply any information regarding *why* two elements are
 considered different.
 """
+from functools import partial
 import numpy as np
 from unittest.util import safe_repr
 from unittest import TestCase
@@ -92,6 +93,9 @@ class Comparison(ComparisonInterface):
     Comparison.assertEqual(matrix1, matrix2)
     """
 
+    # someone might prefer to use a different function, e.g. assert_all_close
+    assert_array_almost_equal_fn = partial(assert_array_almost_equal, decimal=6)
+
     @classmethod
     def register(cls):
 
@@ -246,7 +250,7 @@ def compare_arrays(cls, arr1, arr2, msg='Arrays'):
             assert_array_equal(arr1, arr2)
         except:
             try:
-                assert_array_almost_equal(arr1, arr2)
+                cls.assert_array_almost_equal_fn(arr1, arr2)
             except AssertionError as e:
                 raise cls.failureException(msg + str(e)[11:])