NumPy : Beginner's Guide - Third Edition

Time for action – comparing arrays

Let's compare two arrays with the functions we just mentioned. We will reuse the arrays from the previous Time for action section and add a NaN to them:

1. Call the array_allclose() function:

   print("Pass", np.testing.assert_allclose([0, 0.123456789, np.nan], [0, 0.123456780, np.nan], rtol=1e-7, atol=0))

   The result is as follows:

   Pass None
   

2. Call the array_equal() function:

   print("Fail", np.testing.assert_array_equal([0, 0.123456789, np.nan], [0, 0.123456780, np.nan]))

   The test fails with an AssertionError:

   Fail
   Traceback (most recent call last):
     …
   assert_array_compare
       raise AssertionError(msg)
   AssertionError:
   Arrays are not equal
   
   (mismatch 50.0%)
    x: array([ 0.        ,  0.12345679,         nan])
    y: array([ 0.        ,  0.12345678,         nan])