This function you wrote is interesting, but I almost missed it since I
didn't see a direct example!
cubeValues(NULL, data, indices)
cubeValues(1, data, indices)
cubeValues(c(1,2), data, indices)
(sorry if I'm beating a dead horse here)
On Thu, Aug 4, 2011 at 2:58 PM, R. Michael Weylandt <
michael.weyla...@gmail.com> wrote:
> Hi Jannis,
>
> Like Gene, I'm not entirely sure what your code is intended to do, but it
> wasn't hard to adapt mine to at least print out the desired slice through
> the higher-dimensional array:
>
> cubeValues <- function(Insert, Destination, Location) {
> Location = as.matrix(Location)
> Location = array(Location,dim(Destination))
> if (is.null(Insert)) {
> Destination = round(Destination,3)
> Destination[!Location] = NA
> print(Destination)
> return(invisible())
> }
> Destination[Location] <- Insert
> return(Destination)
> }
>
> If Insert = NULL, it adopts a printing rather than value assigning
> behavior.
>
>
> If you could indicate how you want the values when they come out, it's
> pretty easy to adapt this to do whatever, but I can't just pull out
> subarrays of arbitrary shape while keeping shape: e.g.,
>
> x = matrix(1:4,2,2,byrow=T)
> y = rbind(c(T,F),c(F,T))
>
> > is(x[y])
> "vector"
>
> If you just want the values in a vector, take this version of my code:
>
> cubeValues <- function(Insert, Destination, Location) {
> Location = as.matrix(Location)
> Location = array(Location,dim(Destination))
> if (is.null(Insert)) {
> return(Destination[Location])
> }
> Destination[Location] <- Insert
> return(Destination)
> }
>
> It sounds like you've got what you want, but hopefully this will be of some
> use to anyone who stumbles across this and, like Gene & myself, doesn't
> really get your code.
>
> NB: I have not tested the provided code very much -- it relies on the
> array() function to repeat Location as appropriate. If you know how R
> repeats smaller arrays to make them fit big arrays, this should be fine for
> you -- caveat code-or.
>
> Michael Weylandt
>
> PS -- The combinations() function of the gtools package might be of help to
> you as well. We could get the entire example Gene got by
>
> ans = combinations(1:4,2,repeats.allowed=T)
> rbind(cbind(ans,4),cbind(ans,1))
>
> and it's probably not hard to simplify the entire code as desired.
>
> On Thu, Aug 4, 2011 at 6:33 AM, Jannis <bt_jan...@yahoo.de> wrote:
>
> > Thanks, Michael. I was, however, after a function I coul use for both
> > extracting and replacing subarrays. In case anybody else stumbles over
> this
> > problem, here is my solution. Its programming is most probably horribly
> > clumsy:
> >
> >
> > ind.datacube = function(
> > ##title<< create logical index matrices for multidimensional datacubes
> > datacube ##<< array: datacube from which to extract the subparts
> > , logical.ind ##<< logical array: TRUE/FALSE index matrix for a subset
> of
> > the dimensions
> > ## of datacube. The size of logical.ind`s dimesnions
> has
> > to match the
> > ## sizes of the corresponding dimesnions in datacube.
> > , dims='auto' ##<< integer vector or 'auto' : indices of the dimensions
> > in datacube corresponding
> > ## to the dimensions of logical.ind. If set to 'auto'
> > this matching is tried to
> > ## be accomplished by comparing the sizes of the
> > dimensions of the two objects.
> > )
> > {
> > if (sum(logical.ind) == 0) {
> > stop('No TRUE value in index matrix!')
> > } else {
> > if (dims == 'auto')
> > {
> > if (is.null(dim(logical.ind)[1])) {
> > size.ind = length(logical.ind)
> > logical.ind = matrix(logical.ind,ncol=1)
> > } else {
> > size.ind = dim(logical.ind)
> > }
> > dims = match(size.ind, dim(datacube))
> > if (sum(duplicated(size.ind)) > 0 || sum(duplicated(dims)) > 0
> )
> > stop('dimensions do not match unambigously. Supply dims
> > manually!')
> > }
> > dims.nonapply <- setdiff(1:length(dim(datacube)**),dims)
> > ind.matrix <- which(logical.ind, arr.ind = TRUE)
> >
> > args.expand.grid <- list()
> > counter = 1
> > for (i in 1: length(dim(datacube)))
> > {
> > if (is.element(i,dims.nonapply)) {
> > args.expand.grid[[i]] =
> 1:dim(datacube)[dims.nonapply[**i]]
> > } else {
> > args.expand.grid[[i]] = ind.matrix[,counter]
> > counter = counter + 1
> > }
> > }
> >
> > ind.all <- as.matrix(do.call(expand.grid, args.expand.grid))
> > ind.matrix <- ind.all[,order(c(dims.**nonapply,dims))]
> >
> > }
> > ##value<< integer index matrix which can be used to index datacube
> > ind.matrix
> >
> > }
> >
> >
> > On 08/04/2011 12:12 AM, R. Michael Weylandt <michael.weyla...@gmail.com>
> > wrote:
> >
> >> This might be a little late: but how about this (slightly clumsy)
> >>> function:
> >>>
> >>> putValues<- function(Insert, Destination, Location) {
> >>> Location = as.matrix(Location)
> >>> Location = array(Location,dim(**Destination))
> >>> Destination[Location]<- Insert
> >>> return(Destination)
> >>> }
> >>>
> >>> It currently assumes that the location array lines up in dimension
> order,
> >>> but other than that seems to work pretty well. If you want, it
> shouldn't
> >>> be
> >>> hard to change it to take in a set of dimensions to arrange Location
> >>> along.
> >>> If you like any of the other suggested behaviors, you could put in a
> >>> is.null(Insert) option that returns the desired subset of values. I
> >>> haven't
> >>> tested it completely, but for a few sample inputs, it seems be do as
> >>> desired.
> >>>
> >>> Michael
> >>>
> >>>
> >>> On Wed, Aug 3, 2011 at 5:00 PM, Jannis<bt_jan...@yahoo.de> wrote:
> >>>
> >>> Thanks for all the replies!Unfortunately the solutions only work for
> >>>> extracting subsets of the data (which was exactly what I was asking
> for)
> >>>> and
> >>>> not to replace subsets with other values. I used them, however, to
> >>>> program a
> >>>> rather akward function to do that. Seems I found one of the few
> aspects
> >>>> where Matlab actually is slightly easier to use than R.
> >>>>
> >>>>
> >>>> Thanks for your help!
> >>>> Jannis
> >>>>
> >>>> On 08/01/2011 05:50 PM, Gene Leynes wrote:
> >>>>
> >>>> What do you think about this?
> >>>>>
> >>>>> apply(data, 3, '[', indices)
> >>>>>
> >>>>>
> >>>>> On Mon, Aug 1, 2011 at 4:38 AM, Jannis<bt_jan...@yahoo.de> wrote:
> >>>>>
> >>>>> Dear R community,
> >>>>>
> >>>>>>
> >>>>>> I have a general question regarding indexing in multidiemensional
> >>>>>> arrays.
> >>>>>>
> >>>>>> Imagine I have a three dimensional array and I only want to extract
> on
> >>>>>> vector along a single dimension from it:
> >>>>>>
> >>>>>>
> >>>>>> data<- array(rnorm(64),dim=c(4,4,4))
> >>>>>>
> >>>>>> result<- data[1,1,]
> >>>>>>
> >>>>>> If I want to extract more than one of these vectors, it would now
> >>>>>> really
> >>>>>> help me to supply a logical matrix of the size of the first two
> >>>>>> dimensions:
> >>>>>>
> >>>>>>
> >>>>>> indices<- matrix(FALSE,ncol=4,nrow=4)
> >>>>>> indices[1,3]<- TRUE
> >>>>>> indices[4,1]<- TRUE
> >>>>>>
> >>>>>> result<- data[indices,]
> >>>>>>
> >>>>>> This, however would give me an error. I am used to this kind of
> >>>>>> indexing
> >>>>>> from Matlab and was wonderingt whether there exists an easy way to
> do
> >>>>>> this
> >>>>>> in R without supplying complicated index matrices of all three
> >>>>>> dimensions or
> >>>>>> logical vectors of the size of the whole matrix?
> >>>>>>
> >>>>>> The only way I could imagine would be to:
> >>>>>>
> >>>>>> result<- data[rep(as.vector(indices),******times=4)]
> >>>>>>
> >>>>>> but this seems rather complicated and also depends on the order of
> the
> >>>>>> dimensions I want to extract.
> >>>>>>
> >>>>>>
> >>>>>> I do not want R to copy Matlabs behaviour, I am just wondering
> whether
> >>>>>> I
> >>>>>> missed one concept of indexing in R?
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Thanks a lot
> >>>>>> Jannis
> >>>>>>
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