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 seven 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 eight decimal places):

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

   The result is:

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

What just happened?

We used the assert_almost_equal function from the NumPy testing package to check whether 0.123456789 and 0.123456780 are equal for different decimal precision.

Pop quiz – specifying decimal precision

Q1. Which parameter of the assert_almost_equal...