Neil G Neil G - 1 year ago 135
Python Question

Testing floating point equality

Is there a function to test floating point approximate equality in python? Something like,

def approx_equal(a, b, tol):
return abs(a - b) < tol

My use case is similar to how Google's C++ testing library, gtest.h, defines

Here is an example:

def bernoulli_fraction_to_angle(fraction):
return math.asin(sqrt(fraction))
def bernoulli_angle_to_fraction(angle):
return math.sin(angle) ** 2
def test_bernoulli_conversions():
assert(approx_equal(bernoulli_angle_to_fraction(pi / 4), 0.5, 1e-4))
0.1, 1e-4))

Answer Source
  • For testing numbers, there are and equivalently unittest.assertAlmostEqual
  • For testing numbers or arrays, there is numpy.testing.assert_allclose
  • For comparing numbers, there is math.isclose as per PEP 485 since Python 3.5.
  • For comparing numbers or arrays, there is numpy.allclose.
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