Time for action – asserting approximately equal

Let's take the numbers from the previous Time for action tutorial and let the assert_approx_equal function work on them:

1. Call the function with low significance:

   print "Significance 8", np.testing.assert_approx_
   equal(0.123456789, 0.123456780,
   significant=8)

   The result is:

   Significance 8 None

2. Call the function with high significance:

   print "Significance 9", np.testing.assert_approx_equal(0.123456789, 0.123456780, significant=9)

   An exception is thrown:

   Significance 9
   Traceback (most recent call last):
     ...
   raiseAssertionError(msg)
   AssertionError:
   Items are not equal to 9 significant digits:
    ACTUAL: 0.123456789
    DESIRED: 0.12345678

What just happened?

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