[Numpy-discussion] floats for indexing, reshape - too strict ?

josef.pktd at gmail.com josef.pktd at gmail.com
Thu Jul 2 21:18:57 EDT 2015


On Thu, Jul 2, 2015 at 8:51 PM, Chris Barker - NOAA Federal <
chris.barker at noaa.gov> wrote:

> Sent from my iPhone
>
> >
> > The disadvantage I see is, that some weirder calculations would possible
> > work most of the times, but not always,
>
>
> >  not sure if you can define a "tolerance"
> > reasonable here unless it is exact.
>
> You could use a relative tolerance, but you'd still have to set that.
> Better to put that decision squarely in the user's hands.
>
> > Though I guess you are right that
> > `//` will also just round silently already.
>
> Yes, but if it's in the user's code, it should be obvious -- and then
> the user can choose to round, or floor, or ceiling....
>

round, floor, ceil don't produce integers.

I'm writing library code, and I don't have control over what everyone does.

round, floor, ceil, and // might hide bugs or user mistakes, if we are
supposed to get something that is "like an int" but it's. 42.6 instead.

Josef
https://en.wikipedia.org/wiki/Phrases_from_The_Hitchhiker%27s_Guide_to_the_Galaxy#Answer_to_the_Ultimate_Question_of_Life.2C_the_Universe.2C_and_Everything_.2842.29



>
> -CHB
>
> >
> > - Sebastian
> >
> >>
> >> for example
> >>
> >>
> >>>>> 5.0 == 5
> >> True
> >>
> >>
> >>>>> np.ones(10 / 2)
> >> array([ 1.,  1.,  1.,  1.,  1.])
> >>>>> 10 / 2 == 5
> >> True
> >>
> >>
> >> or the python 2 version
> >>
> >>
> >>>>> np.ones(10. / 2)
> >> array([ 1.,  1.,  1.,  1.,  1.])
> >>>>> 10. / 2 == 5
> >> True
> >>
> >>
> >> I'm using now 10 // 2, or int(10./2 + 1)   but this is unconditional
> >> and doesn't raise if the numbers are not close or equal to an integer
> >> (which would be a bug)
> >>
> >>
> >>
> >>
> >> Josef
> >>
> >>
> >>
> >>
> >> _______________________________________________
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> >> http://mail.scipy.org/mailman/listinfo/numpy-discussion
> >
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