Round half to even on decimal

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Chapters
00:00 Question
01:17 Accepted answer (Score 7)
01:39 Thank you

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Full question
https://stackoverflow.com/questions/2696...

Question links:
[round half to even]: http://en.wikipedia.org/wiki/Rounding#Ro...
[quantize]: https://docs.python.org/2/library/decima...

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Tags
#python #r #rounding

#avk47

ACCEPTED ANSWER

Score 7

The problem is the finite precision of floating point values:

>>> '%.18f' % 1.225
'1.225000000000000089'
>>> '%.18f' % 1.2225
'1.222499999999999920'
>>> '%.18f' % 1.22225
'1.222250000000000059'
>>> '%.18f' % 1.222225
'1.222224999999999895'

Pythons Decimal-class is exact in this sense.