[PYTHON MATRIX-SIG] Handling null data points

[Konrad Hinsen]

> I have two numeric arrays called A and B containing some real data. 
> Missing data has been replaced with a constant 'null' value of 100
> 
>     A = (  20 10 100 6 )
>     B = ( 100  1   2 1 )
> 
> Now if I use Python to calculate A divided by B:
> 
>     C = ( 0.2 10 50 6 ) 
> 
> But when A or B is null I would like the answer to be null:
> 
>     C = ( 100 10 100 6 )
> 

The cleanest solution to your problem would be to define a new
data type, "number with special null value", and define all
the arithmetic operations on it. You could even do that in Python,
or if speed matters as a C extension. But even with a C extension
you would not get the full speed of array operations, since your
arrays would be of "general object" type.

-- 
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Konrad Hinsen                          | E-Mail: hinsen@ibs.ibs.fr
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