Dear Martin, Thank you very much for the (reassuring and helpful) response.
Best regards, Costas On Jun 30, 2010, at 3:58 PM, Martin Maechler wrote: >>>>>> "CA" == Constantinos Antoniou <constantinos.antoniou.rli...@gmail.com> >>>>>> on Wed, 30 Jun 2010 12:07:16 +0300 writes: >>>>>> "CA" == Constantinos Antoniou <constantinos.antoniou.rli...@gmail.com> >>>>>> on Wed, 30 Jun 2010 12:07:16 +0300 writes: > > CA> Dear all (copying the package author), > > CA> I have a question on the vlmc package. I am trying to > CA> model a time series, where each element can take one of > CA> 11 values (the result of some clustering). When I run > CA> the following command (synthetic data to facilitate > CA> self-contained example) > > (very good) > >> I get the following warning: ("alphabet with >1-letter strings; trying to >> abbreviate") > >> +++ START+++ >>> library(VLMC) >>> a <- floor(runif(1000,0,11)) >>> vc <- vlmc(a,cutoff=5) >> Warning message: >> In vlmc(a, cutoff = 5) : >> alphabet with >1-letter strings; trying to abbreviate >>> vc >> 'vlmc' a Variable Length Markov Chain; >> alphabet 'abcdefghijk', |alphabet| = 11, n = 1000. >> Call: vlmc(dts = a, cutoff.prune = 5) > -> extensions (= $size ) : >> ord.MC context nr.leaves total >> 2 72 61 1608 >> AIC = 5247 >>> >> +++ END+++ > >> The questions are: >> 1. What is it trying to do? > > Your contains values 0 1 2 .. 10 > it tries to match them to 1-letter strings, but '10' "is 2 > letters" > >> 2. How is it abbreviating? > > (not really important: using abbreviate() > >> 3. How much should I worry about it? > > not at all. The warning is just to inform you that your input > looks a bit "unusual" to vlmc. > > I do agree however, that one could argue that vlmc() should work > for inputs with values > 0:m > or 1:n > without a warning. > >> 4. What can I do? > > You could use > > vc <- vlmc(letters[1+a], cutoff=5) > > to get the exact same model, but without a warning. > or > vc <- vlmc(a, cutoff=5, quiet = TRUE) > or > vc <- vlmc(a, cutoff=5, code1char = FALSE) > > > >> I have looked at the documentation plus >> M<c3><a4>chler M. and B<c3><bc>hlmann P. (2004) Variable Length Markov >> Chains: >> Methodology, Computing, and Software. _J. Computational and >> Graphical Statistics_ *2*, 435-455. > > That's good. > The examples there all have a character vector (of > strings with 1 letter/character) as input. > > >> Thanks for any feedback, > > You're welcome! > Martin Maechler, ETH Zurich > > >> -- >> Constantinos Antoniou, Ph.D., Assistant Professor >> National Technical University of Athens >> Laboratory of Transportation Engineering >> School of Rural and Surveying Engineering >> 9 Heroon Politechniou st., 15780-Zografou, Athens, Greece >> T: +30 210 7722783 - F: +30 210 7722629 >> anton...@central.ntua.gr - http://users.ntua.gr/antoniou > > >> Dear all (copying the package author), I have a question >> on the vlmc package. I am trying to model a time series, >> where each element can take one of 11 values (the result >> of some clustering). When I run the following command >> (synthetic data to facilitate self-contained example) I >> get the following warning: ("alphabet with >1-letter >> strings; trying to abbreviate") > > > >> +++ START+++ >>> library(VLMC) a <- floor(runif(1000,0,11)) vc <- >>> vlmc(a,cutoff=5) >> Warning message: In vlmc(a, cutoff = 5) : alphabet with >>> 1-letter strings; trying to abbreviate >>> vc >> 'vlmc' a Variable Length Markov Chain; alphabet >> 'abcdefghijk', |alphabet| = 11, n = 1000. Call: >> vlmc(dts = a, cutoff.prune = 5) > -> extensions (= $size ) : >> ord.MC context nr.leaves total 2 72 61 1608 AIC = >> 5247 >>> >> +++ END+++ > >> The questions are: 1. What is it trying to do? 2. How >> is it abbreviating? 3. How much should I worry about >> it? 4. What can I do? > >> I have looked at the documentation plus M<c3><a4>chler >> M. and B<c3><bc>hlmann P. (2004) Variable Length Markov >> Chains: Methodology, Computing, and Software. >> _J. Computational and Graphical Statistics_ *2*, >> 435-455. > > >> Thanks for any feedback, Costas > > > >> -- Constantinos Antoniou, Ph.D., Assistant Professor >> National Technical University of Athens Laboratory of >> Transportation Engineering School of Rural and Surveying >> Engineering 9 Heroon Politechniou st., 15780-Zografou, >> Athens, Greece T: +30 210 7722783 - F: +30 210 7722629 >> anton...@central.ntua.gr - http://users.ntua.gr/antoniou > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.