[Numpy-discussion] Getting masked array boundary indices

[josef.pktd at gmail.com]

On Wed, Nov 27, 2013 at 7:01 AM, Sudheer Joseph
<sudheer.joseph at yahoo.com> wrote:
> Hi,
>                I have a numpy array which is masked ( bathymetry), as seen below
>
>  [ True]
>  [ True]
>  [ True]
>  [ True]],
>        fill_value = -9999.0)
>
>
> In [10]: depth[:,1130:1131]
>
> I need to find the indices where land(mask) is there along the boundaries and where water(value) is there along the boundaries, the above listing is along eastern boundary.
> Please help if there is a way to get  starting and ending index of mask.
> I tried np.where but it gives another array as there are several mask points are there, I need to use some thing like "if neighbouring points are  True and False then" index =i, but I am not getting the pythonic way to  get this done.

if I understand correctly

np.nonzero(np.diff(depth.mask))[0]

Josef

>
> with best regards,
> Sudheer
>
>
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