[Numpy-discussion] copy mask from existing masked array?

Chao YUE chaoyuejoy@gmail....
Sun Mar 4 12:01:55 CST 2012

Dear all,

I have a matrix with dimension of (360,720) but with all global data.
I have another land-sea mask matrix with only 2 unique values in it
(land=1, sea=-1).
So I can easily create transform the second array to a masked array.
the problem is, how can I quickly transform the first one to a masked array
using the same mask as the land-sea mask array?

I hope my question is clear. If not, here is an example:

In [93]: a=np.arange(10).reshape(2,5)
In [95]: a=np.ma.masked_equal(a,2
In [96]: a=np.ma.masked_equal(a,8)

In [97]: a
masked_array(data =
 [[0 1 -- 3 4]
 [5 6 7 -- 9]],
             mask =
 [[False False  True False False]
 [False False False  True False]],
       fill_value = 8)

In [100]: b=np.random.normal(0,2,size=(2,5))

I want to convert b to a masked array using exactly the same mask as a.

thanks to all,

Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:
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