[Numpy-discussion] Question about masked arrays

Gökhan Sever gokhansever@gmail....
Mon Sep 20 15:23:34 CDT 2010


On Mon, Sep 20, 2010 at 1:05 PM, Robert Kern <robert.kern@gmail.com> wrote:

> Are you asking about when masked arrays are casted to ndarrays (and
> thus losing the mask information)? Most times when a function uses
> asarray() or array() to explicitly cast the inputs to an ndarray. The
> reason that np.mean() gives the same result as np.ma.mean() is that it
> simply defers to the .mean() method on the object, so it works as
> expected on a masked array. Many other functions will not.
>
> --
> Robert Kern
>

Right guess. It is important for me to able to preserve masked array
properties of an array. Otherwise losing the mask information yields
unexpected results in some of my calculations. I could see from np.mean??
that mean function is indeed the object method. Also in /numpy/ma there is a
conversion for np.zeros(). I guess in any case it is the user's
responsibility to make sure that the operations are performed on a desired
array type.


-- 
Gökhan
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