Remove masked elements from an array

[Fernando Pérez]

James J. Besemer wrote:

>> No, please heed other advice and use the MA approach. Please note that I'm
>> not dissing this post on its own merits, it's a nice discussion, it just is
>> ill-adapted to numeric processing. Numeric provides its own fast way to
>> manipulate arrays with invalid data, by all means use it. After all, speed
>> is one of the big reasons why you use Numeric to begin with (you could do
>> most things in it with regular lists, if you had the age of the universe to
>> wait).
> 
> I would agree with you that it might be worth the extra trouble and effort
> to download, install and learn to use Numerics IF the user in question has a
> big, production application to run.
> 

Quoting the original post:

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.

/quote

That's why I emphasized to him using Numeric's masked array facilities: 
_because_ he said he was using Numeric to begin with (unless his use of 
'Numeric array' with a capital N misled me, and he just means 'a list with 
numbers in it' ;). All in all I liked the thread because it exposed valuable 
alternative approaches to a problem, and that's always a good way to learn. 
But I assume that if the OP was using Numeric to begin with, performance 
probably is a concern to him in the first place.

Otherwise I was happy to read the various alternatives proposed.

cheers,

f.