Sauvik De schrieb:
> Hi Gabor:
> Many thanks for your prompt reply!
> The code is fine. But I need it in more general form as I had mentioned that
> I need to input any 0 to find its dimension-names.
>
> Actually, I was using "sapply" to calculate correlation and this idea was
> required in the middle of correlation calculation.
> I am providing the way I tried my calculation.
>
> a= c("A1","A2","A3","A4","A5")
> b= c("B1","B2","B3")
> c= c("C1","C2","C3","C4")
> d= c("D1","D2")
> e= c("E1","E2","E3","E4","E5","E6","E7","E8")
>
> DataArray_1 = array(c(rnorm(240)),dim=c(length(a),length(b),
> length(d),length(e)),dimnames=list(a,b,d,e))
> DataArray_2 = array(c(rnorm(320)), dim=c(length(a),length(c),
> length(d),length(e)),dimnames=list(a,c,d,e))
>
> #Defining an empty array which will contain the correlation values (output
> array)
> Correl = array(NA, dim=c(length(a),length(b),
> length(c),length(d)),dimnames=list(a,b,c,d))
>
> #Calculating Correlation between attributes b & c over values of e
> Correl = sapply(Correl,function(d) cor(DataArray_1[...],DataArray_2[...],
> use="pairwise.complete.obs"))
>
> This is where I get stuck.
> In the above, d is acting as an element in the "Correl" array. Hence I need
> to get the dimension-names for d.
>
> #The first element of Correl will be:
> cor(DataArray_1[dimnames(Correl)[[1]][1],dimnames(Correl)[[2]][1],dimnames(Correl)[[4]][1],],DataArray_2[dimnames(Correl)[[1]][1],dimnames(Correl)[[3]][1],dimnames(Correl)[[4]][1],],use="pairwise.complete.obs")
>
> So my problem boils down to extracting the dim-names in terms of element(d)
> and not in terms of Correl (that I have mentioned as "..." in the above
> code)
>
> My sincere thanks for your valuable time & suggestions.
>
> Many Thanks & Kind Regards,
> Sauvik
>
>
> On Sun, Jul 26, 2009 at 5:26 AM, Gabor Grothendieck <ggrothendi...@gmail.com
>
>> wrote:
>>
>
>
>> Try this:
>>
>>
>>> ix <- c(1, 3, 4, 2)
>>> mapply("[", dimnames(mydatastructure), ix)
>>>
>> [1] "S1" "T3" "U4" "V2"
>>
>>
>> On Sat, Jul 25, 2009 at 5:12 PM, Sauvik De<sauvik.s...@gmail.com> wrote:
>>
>>> Hi:
>>> How can I extract the dimension-names of a pre-defined element in a
>>> multidimensional array in R ?
>>>
>>> A toy example is provided below:
>>> I have a 4-dimensional array with each dimension having certain length.
>>>
>> In
>>
>>> the below example, "mydatastructure" explains the structure of my data.
>>>
>>> mydatastructure = array(0,
>>>
>> dim=c(length(b),length(z),length(x),length(d)),
>>
>>> dimnames=list(b,z,x,d))
>>>
>>> where,
>>> b=c("S1","S2","S3","S4","S5")
>>> z=c("T1","T2", "T3")
>>> x=c("U1","U2","U3","U4")
>>> d=c("V1","V2")
>>>
>>> Clearly, "mydatastructure" contains many 0's.
>>> Now how can I get the dimension-names of any particular 0 ?
>>> That is, my input should be a particular 0 in the array "mydatastructure"
>>> (Suppose this 0 corresponds to S1,T3,U4 & V2 in the array). Then my
>>>
>> output
>>
>>> should be S1,T3,U4 & V2.
>>>
>>> The function "dimnames" didn't help me with the solution.
>>> Any idea will greatly be appreciated.
>>>
>>> Thanks for your time!
>>>
>>> Kind Regards,
>>> Sauvik
>>>
>>> [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help@r-project.org mailing list
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>>> PLEASE do read the posting guide
>>>
>> http://www.R-project.org/posting-guide.html
>>
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
Hey,
I have spend some time to write a function, which should fulfill your
needs.
so i hope ;-)
findIndex<-function(data,element) {
ld<-length(data)
el<-which(is.element(data,element))
lel<-length(el)
ndim<-length(dim(data))
ind<-array(,dim=c(lel,ndim),dimnames=list(el,1:ndim))
precomma<-""
tempdata<-data
tempel<-el
for (j in 1:lel) {
data<-tempdata
el<-tempel
ld<-length(data)
for (i in ndim:1) {
ratio<-el[j]/(ld/dim(data)[i])
if (ratio-trunc(ratio)>0) {
ind[j,i]<-trunc(ratio)+1
} else {
ind[j,i]<-trunc(ratio)
}
if (length(dim(data))>1) {
k<-1
while (k>=1 & k<=(i-1)) {
precomma<-paste(precomma,",",sep="")
k<-k+1
}
data<-as.array(eval(parse(text=paste("data[",precomma,ind[j,i],"]",sep=""))))
precomma<-""
ld<-length(data)
el[j]<-which(is.element(data,element))
}
}
}
return(ind)
}
Regards,
Christian Porsche
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