[Numpy-discussion] RecArray.tolist() suggestion

Colin J. Williams cjw at sympatico.ca
Fri Jul 16 19:46:09 CDT 2004


Paul Barrett wrote:

> Russell E Owen wrote:
>
>>> A Divendres 16 Juliol 2004 02:21, Colin J. Williams va escriure:
>>>
>>>>  To allow for multi-word column names, assignment could replace a 
>>>> space
>>>>  by an underscore
>>>>  and, in retrieval, the reverse could be done - ie. underscore 
>>>> would be
>>>>  banned for a column name.
>>>
>>>
>>>
>>> That's not so easy. What about other chars like '/&%@$()' that 
>>> cannot be
>>> part of python names? Finding a biunivocal map between them and allowed
>>> chars would be difficult (if possible at all). Besides, the resulting
>>> colnames might become a real mess.
>>
>>
>>
>> Personally, I think the idea of allowing access to fields via 
>> attributes is fatally flawed. The problems raised (non-obvious 
>> mapping between field names with special characters and allowable 
>> attribute names and also the collision with existing instance 
>> variable and method names) clearly show it would be forced and 
>> non-pythonic.
>
>
> +1

Paul,

Below, I've appended my response to Francesc's 08:36 message, it was 
copied to the list
but does not appear in the archive.

>
> It also make it difficult to do the following:
>
> a = item[:10, ('age', 'surname', 'firstname')]
>
> where field (or column) 1 is 'firstname, field 2 is 'surname', and 
> field 10 is 'age'.
>
> -- Paul

Could you clarify what you have in mind here please?  Is this a proposed
extension to records.py, as it exists in version 1.0?

Colin W.
------------------------------------------------------------------------
Yes, if the objective is to include special characters or facilitate 
multi-lingual columns names and
it probably should be, then my suggestion is quite inadequate.

Perhaps there could be a simple name -> column number mapping in place 
of _names.  References
to a column, or a field in a record, could then be through this dictionary.

Basic access to data in a record would be by position number, rather 
than name, but the dictionary
would facilitate access by name.

Data could be referenced either through the column name: r1.c2[1] or
through the record r1[1].c2, with the possibility that the index is 
multi-dimensional in either case.

Colin W.





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