[Numpy-discussion] metadata and metabehavior for arrays (for scipy.base or Numeric3)

Colin J. Williams cjw at sympatico.ca
Wed Apr 6 03:33:05 EDT 2005

Sébastien de Menten wrote:

> Hi,
> I follow with great interest the threads around Numeric3/scipy.base.
> As Travis suggested (“It would also help if other people who have 
> concerns would voice them (I'm very grateful for those who have 
> expressed their concerns) so that we can all address them and get on 
> the same page for future development.”), I voice my concert J
> Sometimes it is quite useful to treat data at a higher level than just 
> an “array of number of some types”. Adding metadata to array (I called 
> them “augmented arrays”) is a simple way to add sense to an array. I 
> see different user cases like:
> 1) attaching a physical unit to array data (see for instance Unum 
> http://home.tiscali.be/be052320/Unum.html )
> 2) description of axis (see 
> http://sourceforge.net/mailarchive/message.php?msg_id=11051806). Very 
> useful to manipulate easily time series.

Does the record array provide a means of addressing this need?

> 3) masked arrays as in MA module of Numeric
> 4) arrays for interval arithmetic where one keep another array with 
> precision of data
> 5) record arrays (currently being integrated in scipy.base as a base 
> type)
Yes, and there is numarray's array of objects.

> The current solution for those situation is nicely summarized by 
> quoting Konrad
> “but rather a class written using arrays than a variety of the basic 
> array type.
> It’s actually pretty straightforward to implement, the most difficult 
> choice being the form of the constructor that gives most flexibility 
> in use.”

Colin W.

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