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Re: Sets of subsets

by mzedeler (Pilgrim)
on Jul 22, 2009 at 20:59 UTC ( #782440=note: print w/replies, xml ) Need Help??


in reply to Sets of subsets

It is easier to do as many class divisions as you have positions in each tuple (I guess tuple is a better word in stead of set, since you have the same number of elements in each of them):

Class(a1): {{t1, t2, t3}, {t4}} Class(a2): {{t1, t3, t4}, {t2}} Class(a3): {{t1, t4}, {t2, t3}}

While you divide into classes, you'll easilly be able to maintain a distance map like so:

After processing Class(a1): \ t1 | t2 | t3 | t4 t1 0 | 0 | 0 | 1 t2 0 | 0 | 1 t3 0 | 1 t4 0 After processing Class(a2): \ t1 | t2 | t3 | t4 t1 0 | 1 | 0 | 1 t2 0 | 1 | 2 t3 0 | 1 t4 0 After processing Class(a3): \ t1 | t2 | t3 | t4 t1 0 | 2 | 1 | 1 t2 0 | 1 | 3 t3 0 | 2 t4 0

This way, you can get complexity O(m * n) where m is the number of tuples and n is the size of the tuples.

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[ambrus]: Corion: as for that, I talked with schmorp, and looked a bit more at Prima
[ambrus]: Corion: from the docs, it definitely looks like it would be possible to write an AnyEvent driver for it using Prima::File and Prima::Timer.
[ambrus]: (I haven't found an idle event.)
[ambrus]: However, I also looked at the internals, and found two interesting things:
[marto]: stupid xpath question, I have a xpath copied from the browser, is the * wildcard supposed to work for IDs? e.g. '//*[@id="*"]/ div/div/header/p/a '?
[ambrus]: The main loop for unixish systems is in https://metacpan. org/source/ KARASIK/Prima-1. 49/unix/apc_app.c. It is a hand-rolled select loop, but also always spins at least once every 0.2 seconds for some reason.
[ambrus]: marto: no, not that way. if you just want to test for an existing id attribute, then write *[@id] , or you can match a regexp to the value of that attribute like *[@id=~/something/ ]
[marto]: ambrus, thanks I ended up going with '//*[starts- with(@id, "thread_")]...

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