[SciPy-dev] Numpy example for arctan2 perhaps wrong/misleading/confusing?

David Huard david.huard@gmail....
Tue Jun 10 07:42:23 CDT 2008


2008/6/10 Anne Archibald <peridot.faceted@gmail.com>:

> 2008/6/9 David Huard <david.huard@gmail.com>:
> > Samuel,
> >
> > What you want is this :
> >
> >> [4]: def arctan2(vectors):
> >    ...:     """Return the angle between the x axis and each vector in
> > vectors."""
> >    ...:     v = np.atleast_2d(vectors)
> >    ...:     return np.arctan2(v[:,0], v[:,1])
> >    ...:
> >
> >> [5]: arctan2(([0,0], [1,0]))
> > < [5]: array([ 0.        ,  1.57079633])
> >
> >
> > You could also use the numpy.angle function which returns the angle of a
> > complex argument.
> >
> >> [15]: np.angle([0, 1j])
> >  <[15]: array([ 0.        ,  1.57079633])
>
> Just a detail, but it would probably be better to write
> np.arctan2(v[...,0], v[...,1]) (and then drop the atleast_2d). This
> then works for arbitrarily-dimensioned arrays.
>

Nice.

Thanks for the pointer,

David


>
> Anne
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