[R] learning networks with a large number of variables andpre-set parents.
lzhtom at hotmail.com
Sat Mar 26 07:23:04 CET 2005
I didn't go into details when I asked the question for feat that I would
overly specific and blur my real goals.
The links between variables are defined as conditional probability
distributions. So if the probability distribution of a variable X's value
is conditioned on the probability distribution of the values of Y and Z, we
say Y and Z are X's parents, and in the network, there are two arrows
starting from Y and Z and poining both to X.
Clearly it's something like a bayesian network. And I do know some
packages, such as deal, can learn the bayesian networks structure from
training data. But I'm not sure if deal or other similar packages can
handle 10000 variables......
Thanks a lot for your information.
>From: "Shelby Berkowitz" <berkowi4 at msu.edu>
>To: "'zhihua li'" <lzhtom at hotmail.com>
>Subject: RE: [R] learning networks with a large number of variables
>Date: Fri, 25 Mar 2005 10:00:17 -0500
>It's not really clear to me what it is you're trying to do, how you've
>defined links between these variables, or how you're defining 'highest
>scoring network', but for manipulating a network of that size you might
>want to check out Pajek http://vlado.fmf.uni-lj.si/pub/networks/pajek/
>network analysis software - there is probably a way from there to
>extract the network you want, and you can export from it back into R for
> >-----Original Message-----
> >From: r-help-bounces at stat.math.ethz.ch
> >[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Achim Zeileis
> >Sent: Friday, March 25, 2005 5:41 AM
> >To: zhihua li
> >Cc: r-help at stat.math.ethz.ch
> >Subject: Re: [R] learning networks with a large number of
> >variables andpre-set parents.
> >This is the second time within 24 hours that you cross-posted
> >the same question to two of the R mailing lists, please read
> >the posting guide linked at the bottom of this mail on how to
> >properly ask your questions.
> >As for your question: I'm not aware of an R package that would
> >be able to do what you are looking for, but you might also ask
> >the maintainer of the package you're specifically interested
> >in for more details. Z
> >On Fri, 25 Mar 2005, zhihua li wrote:
> >> hi netters:
> >> I have a series of discrete variables which form a network and I
> >> want to learn the network structure from some training data. I could
> >> have used packages like deal but there are two problems.
> >> First of all, I have 10000 variables. So the possible network
> >> structure is awfully huge, I don't know how long it will
> >take my PC to
> >> find the highest-scoring network..........maybe a month? Secondly, I
> >> have some prior knowledge that only 500 out of the 10000
> >variales are
> >> possible parents. In another word, only those arrows startting from
> >> the 500 variables and pointing to the remaining 99500 variables are
> >> allowed in the network. In deal an assignment to "banlist" should
> >> help me rule out the impossible arrows. But in my case the number of
> >> "impossible arrows" is 500*499+99500*99549, and so the "banlist"
> >> would get unacceptable long. Are there any methods (in deal or other
> >> packages) to specify the parents set in advance?
> >> Thanks a lot!
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