mask one array using another array

[questions anon]

I am trying to mask one array using another array.

I have created a masked array using
mask=MA.masked_equal(myarray,0),
that looks something like:
[1  -  -  1,
 1  1  -  1,
 1  1  1  1,
 -   1  -  1]

I have an array of values that I want to mask whereever my mask has a a '-'.
how do I do this?
I have looked at
http://www.cawcr.gov.au/bmrc/climdyn/staff/lih/pubs/docs/masks.pdf but the
command:

d = array(a, mask=c.mask()

results in this error:
TypeError: 'numpy.ndarray' object is not callable

I basically want to do exactly what that article does in that equation.

Any feedback will be greatly appreciated.
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