Python 错误查找胭脂的解决方法
到目前为止,一切顺利。但现在:Python 错误查找胭脂的解决方法,python,floating-accuracy,Python,Floating Accuracy,到目前为止,一切顺利。但现在: $ python Python 2.7.3 (default, Apr 19 2012, 11:28:02) [GCC 4.5.3 20120403 (ALT Linux 4.5.3-alt3)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> g = 1.175 >>> "%0.2f" % g '1.18
$ python
Python 2.7.3 (default, Apr 19 2012, 11:28:02)
[GCC 4.5.3 20120403 (ALT Linux 4.5.3-alt3)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> g = 1.175
>>> "%0.2f" % g
'1.18'
>>> g = 11.175
>>> "%0.2f" % g
'11.18'
“111.17”而不是预期的“111.18”。我想我知道发生了什么,为什么会发生,但我需要知道如何得到预期的结果。Excel和OpenOffice Calc都显示“111.18”,因此,无论如何,这应该是可能的。您可以在此处使用该模块:
>>> g = 111.175
>>> "%0.2f" % g
'111.17'
我假设Excel和OpenOffice Calc不使用浮点数,至少不直接在UI中公开。
>>> import decimal
>>> myothercontext = decimal.Context(rounding=decimal.ROUND_HALF_UP)
>>> decimal.setcontext(myothercontext)
>>> TWOPLACES = decimal.Decimal(10) ** -2
>>> decimal.Decimal('111.175').quantize(TWOPLACES)
Decimal('111.18')
>>> decimal.Decimal('1.175').quantize(TWOPLACES)
Decimal('1.18')
>>> decimal.Decimal('11.175').quantize(TWOPLACES)
Decimal('11.18')