Remove masked elements from an array

[holger krekel]

On Mon, Apr 29, 2002 at 01:26:25PM -0400, PoulsenL at capecon.com wrote:
> I have a Numeric array with missing elements from which I wish to calculate
> a histogram.  However, in order to do so I must first remove the 'None'
> values from the array.  I have a kludgy solution, but I was wondering if
> someone could point me in the right direction on what is the proper method
> of collapsing a masked array to just the non-masked values.

there are too solutions. choose yourself :-)

nums = [ 1,2,3,None,2,3]

#version1
def f(x): return x is not None
newnums = filter(f, nums)

#version2
newnums = [ x for x in nums if x is not None]

The first version uses filter. 
'filter' calls 'f' for every item in 'nums' and puts
the result into the new list iff it has a 'true' value.

The second version uses list comprehension.
It basically does the same if you look closely
at it. 

regards,

    holger