[Numpy-discussion] Another masked array question

[Gökhan Sever]

On Sat, May 8, 2010 at 9:16 PM, Ryan May <rmay31 at gmail.com> wrote:

> On Sat, May 8, 2010 at 7:52 PM, Gökhan Sever <gokhansever at gmail.com>
> wrote:
> > Hello,
> >
> > Consider my masked arrays:
> >
> > I[28]: type basic.data['Air_Temp']
> > -----> type(basic.data['Air_Temp'])
> > O[28]: numpy.ma.core.MaskedArray
> >
> > I[29]: basic.data['Air_Temp']
> > O[29]:
> > masked_array(data = [-- -- -- ..., -- -- --],
> >              mask = [ True  True  True ...,  True  True  True],
> >        fill_value = 999999.9999)
> >
> >
> > I[17]: basic.data['Air_Temp'].data =
> np.ones(len(basic.data['Air_Temp']))*30
> >
> ---------------------------------------------------------------------------
> > AttributeError                            Traceback (most recent call
> last)
> >
> > ----> 1
> >       2
> >       3
> >       4
> >       5
> >
> > AttributeError: can't set attribute
> >
> > Why this assignment fails? I want to set each element in the original
> > basic.data['Air_Temp'].data to another value. (Because the main
> instrument
> > was forgotten to turn on for that day, and I am using a secondary
> > measurement data for Air Temperature for my another calculation. However
> it
> > fails. Although single assignment works:
> >
> > I[13]: basic.data['Air_Temp'].data[0] = 30
> >
> > Shouldn't this be working like the regular NumPy arrays do?
>
> Based on the traceback, I'd say it's because you're trying to replace
> the object pointed to by the .data attribute. Instead, try to just
> change the bits contained in .data:
>
> basic.data['Air_Temp'].data[:] = np.ones(len(basic.data['Air_Temp']))*30
>
> Ryan
>
> --
> Ryan May
> Graduate Research Assistant
> School of Meteorology
> University of Oklahoma
>

Thanks for the pointer Ryan. Now it works as it is supposed to be.

-- 
Gökhan
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