Re: [Numpy-discussion] adding an attribute to an nd-array

[Stefan v. d. W. <st...@su...>]

On Thu, Oct 19, 2006 at 09:45:02AM -0600, Travis Oliphant wrote:
> Stefan van der Walt wrote:
>=20
> >If I understand correctly, the following should work:
> >
> >import numpy as N
> >
> >class InfoArray(N.ndarray):
> >    def __new__(info_arr_cls,arr,info=3D{}):
> >        info_arr_cls.info =3D info
> >        return N.array(arr).view(info_arr_cls)

One has to be careful of this approach.  It ads *the same* information
to all arrays, i.e.

In [2]: a =3D ImageInfo(N.array([1,2,3]),{1:1})

In [3]: b =3D ImageInfo(N.array([1,2,3]),{1:2})

In [4]: a
Out[4]: ImageInfo([1, 2, 3])

In [5]: b
Out[5]: ImageInfo([1, 2, 3])

In [6]: a.info
Out[6]: {1: 2}

In [7]: b.info
Out[7]: {1: 2}

Regards
St=E9fan