[Numpy-discussion] Rename record array fields (with object arrays)

Sameer DCosta sameerslists@gmail....
Thu Feb 28 14:00:45 CST 2008


I think having a record array field renaming api is a good idea.. I
was going to create a ticket for this, but I don't think I have
permissions to do this. Can someone who has the permissions, please
create it? Thanks.

Sameer

On Thu, Feb 28, 2008 at 10:48 AM, Travis E. Oliphant
<oliphant@enthought.com> wrote:
>
> Sameer DCosta wrote:
>  > Hi,
>  >
>  > I'm having trouble renaming record array fields if they contain object
>  > arrays in them. I followed the solutions posted by Robert Kern and
>  > Stefan van der Walt  (Thanks again) but it doesn't look like this
>  > method works in all cases. For reference:
>  > http://projects.scipy.org/pipermail/numpy-discussion/2008-February/031509.html
>  >
>  > In [1]: from numpy import *
>  >
>  > In [2]: olddt = dtype([('foo', '|O4'), ('bar', float)])
>  >
>  > In [3]: a = zeros(10, olddt)
>  >
>  > In [4]: a
>  > Out[4]:
>  > array([(0, 0.0), (0, 0.0), (0, 0.0), (0, 0.0), (0, 0.0), (0, 0.0),
>  >        (0, 0.0), (0, 0.0), (0, 0.0), (0, 0.0)],
>  >       dtype=[('foo', '|O4'), ('bar', '<f8')])
>  >
>  > In [5]: newdt = dtype([('notfoo', '|O4'), ('notbar', float)])
>  >
>  > In [6]: b = a.view(newdt)
>  > ---------------------------------------------------------------------------
>  > TypeError                                 Traceback (most recent call last)
>  >
>  > /home/titan/sameer/projects/<ipython console>
>  >
>  > TypeError: Cannot change data-type for object array.
>  >
>
>  This looks like a bug.  We are being a bit over-zealous in protecting
>  you from getting access to pointers and in the process making it
>  impossible to rename Object fields.
>
>  Perhaps an actual field-renaming API (which would be relatively easy) is
>  useful.
>
>  -Travis O.
>


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