[Numpy-discussion] question about a data structure

Robert Kern robert.kern@gmail....
Wed Jul 29 16:39:01 CDT 2009

2009/7/29 Ernest Adrogué <eadrogue@gmx.net>:
> Hello,
> Suppose I want to store some data (a non-negative integer)
> related to an "event" involving two entities. It occurs to me that
> the way to do it is using a 2-d array, like a table:
> For example:
>  a  b  c
> a    1
> b 2     0
> c 5
> in the event 'b-a' the data is 2, and in the event 'c-a' is 5, etc.
> Now, I need to be able to differentiate between 0 and 'no data'.
> I know I could use a number like -1, but this would affect arithmetic
> operations on the array, and also I need that indexing one such
> location with no data returns an empty array.
> Is it possible to do this with the standard array class?

Not really. Use masked arrays. Or use a dictionary.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco

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