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Issue #4707: round(x, n) now returns an integer when x is an integer.

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Previously it returned a float.
This commit is contained in:
Mark Dickinson 2009-01-28 21:25:58 +00:00
parent 9de29afa7c
commit 1124e71368
5 changed files with 217 additions and 33 deletions
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75
Lib/test/test_long.py
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@ -896,6 +896,81 @@ class LongTest(unittest.TestCase):
self.assertEqual((a+1).bit_length(), i+1)
self.assertEqual((-a-1).bit_length(), i+1)
def test_round(self):
# check round-half-even algorithm. For round to nearest ten;
# rounding map is invariant under adding multiples of 20
test_dict = {0:0, 1:0, 2:0, 3:0, 4:0, 5:0,
6:10, 7:10, 8:10, 9:10, 10:10, 11:10, 12:10, 13:10, 14:10,
15:20, 16:20, 17:20, 18:20, 19:20}
for offset in range(-520, 520, 20):
for k, v in test_dict.items():
got = round(k+offset, -1)
expected = v+offset
self.assertEqual(got, expected)
self.assert_(type(got) is int)
# larger second argument
self.assertEqual(round(-150, -2), -200)
self.assertEqual(round(-149, -2), -100)
self.assertEqual(round(-51, -2), -100)
self.assertEqual(round(-50, -2), 0)
self.assertEqual(round(-49, -2), 0)
self.assertEqual(round(-1, -2), 0)
self.assertEqual(round(0, -2), 0)
self.assertEqual(round(1, -2), 0)
self.assertEqual(round(49, -2), 0)
self.assertEqual(round(50, -2), 0)
self.assertEqual(round(51, -2), 100)
self.assertEqual(round(149, -2), 100)
self.assertEqual(round(150, -2), 200)
self.assertEqual(round(250, -2), 200)
self.assertEqual(round(251, -2), 300)
self.assertEqual(round(172500, -3), 172000)
self.assertEqual(round(173500, -3), 174000)
self.assertEqual(round(31415926535, -1), 31415926540)
self.assertEqual(round(31415926535, -2), 31415926500)
self.assertEqual(round(31415926535, -3), 31415927000)
self.assertEqual(round(31415926535, -4), 31415930000)
self.assertEqual(round(31415926535, -5), 31415900000)
self.assertEqual(round(31415926535, -6), 31416000000)
self.assertEqual(round(31415926535, -7), 31420000000)
self.assertEqual(round(31415926535, -8), 31400000000)
self.assertEqual(round(31415926535, -9), 31000000000)
self.assertEqual(round(31415926535, -10), 30000000000)
self.assertEqual(round(31415926535, -11), 0)
self.assertEqual(round(31415926535, -12), 0)
self.assertEqual(round(31415926535, -999), 0)
# should get correct results even for huge inputs
for k in range(10, 100):
got = round(10**k + 324678, -3)
expect = 10**k + 325000
self.assertEqual(got, expect)
self.assert_(type(got) is int)
# nonnegative second argument: round(x, n) should just return x
for n in range(5):
for i in range(100):
x = random.randrange(-10000, 10000)
got = round(x, n)
self.assertEqual(got, x)
self.assert_(type(got) is int)
for huge_n in 2**31-1, 2**31, 2**63-1, 2**63, 2**100, 10**100:
self.assertEqual(round(8979323, huge_n), 8979323)
# omitted second argument
for i in range(100):
x = random.randrange(-10000, 10000)
got = round(x)
self.assertEqual(got, x)
self.assert_(type(got) is int)
# bad second argument
bad_exponents = ('brian', 2.0, 0j, None)
for e in bad_exponents:
self.assertRaises(TypeError, round, 3, e)
def test_main():
support.run_unittest(LongTest)