Re: [R] vector manipulations

From: Pete Dorothy <croero_at_gmail.com>
Date: Tue, 04 Mar 2008 19:17:35 +0100

Thank you very much to both of you, and especially you Phil.

I will tell you if it works.

2008/3/4, Phil Spector <spector_at_stat.berkeley.edu>:
>
> Pete -
> As others have told you, outer only works with vectorized
> functions. An alternative is to use expand.grid to find all
> the combinations of beta and zeta, and then use apply to
> calculate your likelihood for each row. I believe that this
> will work:
>
> allvals = expand.grid(beta=seq(0.1,0.5,by=10^(-1)),zeta=seq(0.1,0.5
> ,by=10^(-1)))
> answer = cbind(allvals,result =
> apply(allvals,1,function(x)logl(x[1],x[2])))
>
> The columns of answer will be named beta, zeta and result, with
> (hopefully) obvious meanings.
>
> - Phil Spector
> Statistical Computing Facility
> Department of Statistics
> UC Berkeley
> spector_at_stat.berkeley.edu

>
>
>
>
> On Tue, 4 Mar 2008, Pete Dorothy wrote:
>
> > Hello,
> >
> > I have simulated a set of data which i called "nir" (a vector).
> >
> > I have created a function "logl" which calculates the log-likelihood.
> >
> > logl is a function of 2 real parameters : "beta" and "zeta" (of length
> 1).
> >
> > This function works perfectly well when I try for example "logl(0.1,0.2
> )"
> >
> > Now if I try :
> >
> > "x=seq(0.1,0.5,by=10^(-1))
> > y=seq(0.1,0.5,by=10^(-1))
> > z=outer(x,y,logl)"
> >
> > I get an error.
> >
> > The problem seems to be that inside "logl", the following expression is
> > calculated : "sum( log( beta+(nir-1)*zeta ) )". So it is a vector
> > manipulation. The error tells me that "nir" is not the size of "zeta".
> Yet
> > usually it is no problem since "length(zeta)=1".
> >
> > When I replace "sum( log( beta+(nir-1)*zeta ) )" by a loop, I get no
> > mistake. But I think it slows down the program.
> >
> > Do you have an idea where the problem is ?
> >
> > Thank you very much.
> >
>
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help_at_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.
> >
>

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