Unexpected results comparing float to Fraction
Steven D'Aprano
steve+comp.lang.python at pearwood.info
Mon Jul 29 11:43:24 EDT 2013
Comparing floats to Fractions gives unexpected results:
# Python 3.3
py> from fractions import Fraction
py> 1/3 == Fraction(1, 3)
False
but:
py> 1/3 == float(Fraction(1, 3))
True
I expected that float-to-Fraction comparisons would convert the Fraction
to a float, but apparently they do the opposite: they convert the float
to a Fraction:
py> Fraction(1/3)
Fraction(6004799503160661, 18014398509481984)
Am I the only one who is surprised by this? Is there a general rule for
which way numeric coercions should go when doing such comparisons?
--
Steven
More information about the Python-list
mailing list