[R] dimnames in an array(I'll be grateful if this message will be passed to all list users)

[R. Michael Weylandt]

On Mon, Aug 13, 2012 at 5:10 AM, aleksandr russell <sss736 at gmail.com> wrote:
> Hello,
>
> I'm hoping someone with a wide experience with R may be able to see
> what the program is trying to tell me.
>
> I've got an array:
>
> y1=rnorm(41,0.2)
> y2=rnorm(41,0.2)
> y3=rbind(y1,y2)
>
>
>
> data11<-array(0,c(41,2,2))
> data11[,1,]=y3
> data11[,2,]=y3
> rownames(data11)<-rownames(data11, do.NULL = FALSE, prefix = "Obs.")
> colnames=c("V","R")
> varnames=c("one","two")
> dimnames(data11)<-list(rownames(data11), varnames, colnames)
>
>
>
> data11a<-as.array(data11, dimnames=dimnames(data11))

# No effect here
 identical(data11, data11a) # TRUE

>
> The analysis that I would like to do with R(CollocInfer) runs as
> follows(I print for the sake of introduction here though to run this
> line of code requires extensive setup)
>
> res11a = inneropt(coefs, times=times, data=data11a, lik=lik,
> proc=proc, pars=spars, in.meth='nlminb', control.in=control.out)
>
>
>
> The response I get is
>
> Error in 'colnames<-'('*tmp*', value = c("V","R")) :
>    length of 'dimnames' [2] not equal to array extent
>
>
>
> It seems to me that there is a fundamental match of 'dimnames' with
> the array that is being referred to.
>
> I have learned that the normal length of dimnames for an array is one
> for each element in the list: thus as I've set up the array, the
> length(dimnames(data11a)[2]) gives me
>
> [1]

I believe you are looking for

length(dimnames(data11a)[[2]]) # 2

Look into the difference between `[` and `[[` for subsetting a list.
See ?Extract for the gorey details, but I like my little train
metaphor:

If the list "x", is a train: x[2] is the "sub-train" consisting only
of the second car, while x[[2]] is the contents of that second car.
Hence we can do x[1:3] to give a well defined train, but not x[[1:3]]
because we have no way to combine the elements of the first three cars
other than using a train.

Cheers,
Michael

>
> I would like to ask :Is it not evident from R's response that there is
> some other possibility for the dimnames[2] of the array?
>
> If so, what is it?
>
> regards,
> A
>
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