holoviews.element.comparison module

Helper classes for comparing the equality of two HoloViews objects.

These classes are designed to integrate with unittest.TestCase (see the tests directory) while making equality testing easily accessible to the user.

For instance, to test if two Matrix objects are equal you can use:

Comparison.assertEqual(matrix1, matrix2)

This will raise an AssertionError if the two matrix objects are not equal, including information regarding what exactly failed to match.

Note that this functionality could not be provided using comparison methods on all objects as comparison operators only return Booleans and thus would not supply any information regarding why two elements are considered different.

class holoviews.element.comparison.Comparison

Bases: ComparisonInterface

Class used for comparing two HoloViews objects, including complex composite objects. Comparisons are available as classmethods, the most general being the assertEqual method that is intended to work with any input.

For instance, to test if two Image objects are equal you can use:

Comparison.assertEqual(matrix1, matrix2)

assert_array_almost_equal_fn(desired, *, decimal=6, err_msg='', verbose=True)

Raises an AssertionError if two objects are not equal up to desired precision.

Note

It is recommended to use one of assert_allclose, assert_array_almost_equal_nulp or assert_array_max_ulp instead of this function for more consistent floating point comparisons.

The test verifies identical shapes and that the elements of actual and desired satisfy:

abs(desired-actual) < 1.5 * 10**(-decimal)

That is a looser test than originally documented, but agrees with what the actual implementation did up to rounding vagaries. An exception is raised at shape mismatch or conflicting values. In contrast to the standard usage in numpy, NaNs are compared like numbers, no assertion is raised if both objects have NaNs in the same positions.

Parameters:

actualarray_like

The actual object to check.

desiredarray_like

The desired, expected object.

decimalint, optional

Desired precision, default is 6.

err_msgstr, optional

The error message to be printed in case of failure.

verbosebool, optional

If True, the conflicting values are appended to the error message.

Raises:

AssertionError

If actual and desired are not equal up to specified precision.

See also

assert_allclose

Compare two array_like objects for equality with desired relative and/or absolute precision.

assert_array_almost_equal_nulp, assert_array_max_ulp, assert_equal

Examples

the first assert does not raise an exception

>>> np.testing.assert_array_almost_equal([1.0,2.333,np.nan],
...                                      [1.0,2.333,np.nan])

>>> np.testing.assert_array_almost_equal([1.0,2.33333,np.nan],
...                                      [1.0,2.33339,np.nan], decimal=5)
Traceback (most recent call last):
    ...
AssertionError:
Arrays are not almost equal to 5 decimals

Mismatched elements: 1 / 3 (33.3%)
Max absolute difference among violations: 6.e-05
Max relative difference among violations: 2.57136612e-05
 ACTUAL: array([1.     , 2.33333,     nan])
 DESIRED: array([1.     , 2.33339,     nan])

>>> np.testing.assert_array_almost_equal([1.0,2.33333,np.nan],
...                                      [1.0,2.33333, 5], decimal=5)
Traceback (most recent call last):
    ...
AssertionError:
Arrays are not almost equal to 5 decimals

nan location mismatch:
 ACTUAL: array([1.     , 2.33333,     nan])
 DESIRED: array([1.     , 2.33333, 5.     ])

class holoviews.element.comparison.ComparisonInterface

Bases: object

This class is designed to allow equality testing to work seamlessly with unittest.TestCase as a mix-in by implementing a compatible interface (namely the assertEqual method).

The assertEqual class method is to be overridden by an instance method of the same name when used as a mix-in with TestCase. The contents of the equality_type_funcs dictionary is suitable for use with TestCase.addTypeEqualityFunc.

classmethod assertEqual(first, second, msg=None)

Classmethod equivalent to unittest.TestCase method

failureException

alias of AssertionError

classmethod simple_equality(first, second, msg=None)

Classmethod equivalent to unittest.TestCase method (longMessage = False.)

class holoviews.element.comparison.ComparisonTestCase(*args, **kwargs)

Bases: Comparison, TestCase

Class to integrate the Comparison class with unittest.TestCase.

class holoviews.element.comparison.IPTestCase(*args, **kwargs)

Bases: ComparisonTestCase

This class extends ComparisonTestCase to handle IPython specific objects and support the execution of cells and magic.

cell(line)

Run an IPython cell

cell_magic(*args, **kwargs)

Run an IPython cell magic

line_magic(*args, **kwargs)

Run an IPython line magic

setUp()

Hook method for setting up the test fixture before exercising it.

tearDown() → None

Hook method for deconstructing the test fixture after testing it.