On Fri, Sep 13, 2019 at 12:58 PM Irvin Probst <irvin.probst@ensta-bretagne.fr> wrote:
Hi, Is it expected/documented that np.round and np.set_printoptions do not output the same result on screen ? I tumbled into this running this code:
import numpy as np mes = np.array([ [16.06, 16.13, 16.06, 16.00, 16.06, 16.00, 16.13, 16.00] ])
avg = np.mean(mes, axis=1) print(np.round(avg, 2)) np.set_printoptions(precision=2) print(avg)
Which outputs:
[16.06] [16.05]
Is that worth a bug report or did I miss something ? I've been able to reproduce this on many windows/linux PCs with python/numpy releases from 2017 up to last week.
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Hi, I just want to add that you can use literal 16.055 to reproduce this:
import numpy as np np.set_printoptions(precision=2) np.array([16.055]).round(2) array([16.06]) np.array([16.055]) array([16.05])
I would think it has to do with "round to nearest even":
np.array(16.055) array(16.05) np.array(16.065) array(16.07) np.array(16.065).round(2) 16.07
But it's as if `round` rounded decimal digits upwards (16.055 -> 16.06, 16.065 -> 16.07), whereas the `repr` rounded to the nearest odd(!) digit (16.055 -> 16.05, 16.065 -> 16.07). Does this make any sense? I'm on numpy 1.17.2. (Scalars or 1-length 1d arrays don't seem to make a difference). Regards, András