NumPy : Beginner's Guide - Third Edition

Time for action – asserting almost equal

Imagine that you have two numbers that are almost equal. Let's use the assert_almost_equal() function to check whether they are equal:

1. Call the function with low precision (up to 7 decimal places):

   print("Decimal 6", np.testing.assert_almost_equal(0.123456789, 0.123456780, decimal=7))

   Note that no exception is raised, as you can see in the following result:

   Decimal 6 None
   

2. Call the function with higher precision (up to 8 decimal places):

   print("Decimal 7", np.testing.assert_almost_equal(0.123456789, 0.123456780, decimal=8))

   The result is as follows:

   Decimal 7
   Traceback (most recent call last):
     …
     raise AssertionError(msg)
   AssertionError:
   Arrays are not almost equal
    ACTUAL: 0.123456789
    DESIRED: 0.12345678