programming unlimited "categories" in python ?

Lucio Torre lucio at movilogic.com
Tue Oct 23 21:11:54 CEST 2001


At 08:32 PM 23/10/2001 +0200, Gabriel Ambuehl wrote:
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>
>Hello Lucio,
>
>Tuesday, October 23, 2001, 6:49:03 PM, you wrote:
>
> >>You still need a link between the two, else you haven't got any
> >>chance
> >>to match them anyway so why not just build the region tree and
> >>store all the data under it? then you query for africa first and
> >>fetch only the results which have got the attribute deadly in 5
> >>hours?
> > you can match them using intersections. you get all the children
> > for every node in all the categories you want, then intersect them
> > all.
>
>But you can only intersect them if you have some additional
>information about which apply to which he


if i have a tree, i can get the children from one node.
if i have two list of children, i can compare them and see where they 
intersect. (equal records)

not the prettiest thing to do in sql maybe. but thats how you cross both 
selections. as i said, the categorization data is not in the data point 
structure, but in the tree. and thats how you get unlimited.

>nce you need some kind of
>link.
>
> >>I wasn't thinking about the implementation itself but mostly about
> >>suitable approaches. IMHO, you should try to squeeze your data
> >>model into ONE tree and the problem is almost solved.
> > so you do this tree:
>
> > africa
>- ->> mozambique
>- -- >> capital
>- ---->> deadly
>- ------>> really deadly
>- ------>> not so deadly
>- --->> deadly
>- ----->> really deadly
>- ----->> not so deadly
>- -->> deadly
>- ---->> really deadly
>- ---->> not so deadly
>- ->> deadly
>- --->> really deadly
>- --->> not so deadly
>
> > but suppose you suddently have cases of a kinda deadly thing. you
> > have to edit the whole tree!
>
>Why? Personally, I'd simply save the deadly stuff in a string (or
>even
>integer) so I can easily add another mode if need be.
>
> > but you can have that if you hard code the tree. but what if you
> > have some subset (really deadly, or spooky deadly.. or whatever, in
> > the query you are doing) and want to find out the africa tree?
>
>I think Python's polymorphism allows for a not so hard coded
>kind of tree as Python won't care what type of object you put into
>data...

yeah, but thins thing you are propossing, is one of the reasons people want 
to switch from RDBMS to OODMS! and we are dealing with sql here.

lucio





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