# [R] uneven list to matrix

Christopher Marcum cmarcum at uci.edu
Fri Aug 24 06:56:35 CEST 2007

```Hi Gabor,

Thank you. The native solution works just fine, though there is an
interesting side effect, namely, that with very large lists the rows of
the output become scrambled though the corresponding columns are correctly
sorted. The zoo package solution does not work on large lists: there is an
error:

Error in order(na.last, decreasing, ...) :
argument 1 is not a vector

Thanks again,

-Chris

Gabor Grothendieck wrote:
> Here are two solutions.  The first repeatedly uses merge and the
> second creates a zoo object from each alph component whose time
> index consists of the row labels and uses zoo's multiway merge to
> merge them.
>
> # test data
> m <- matrix(1:5, 5, dimnames = list(LETTERS[1:5], NULL))
> alph <- list(m[1:4,,drop=F], m[c(1,3,4),,drop=F], m[c(1,4,5),,drop=F])
> alph
>
> # solution 1
> out <- alph[]
> for(i in 2:length(alph)) {
> 	out <- merge(out, alph[[i]], by = 0, all = TRUE)
> 	row.names(out) <- out[]
> 	out <- out[-1]
> }
> matrix(as.matrix(out), nrow(out), dimnames=list(rownames(out),NULL))
>
> # solution 2
> library(zoo)
> z <- do.call(merge, lapply(alph, function(x) zoo(c(x), rownames(x))))
> matrix(coredata(z), nrow(z), dimnames=list(time(z),NULL))
>
>
> On 8/23/07, Christopher Marcum <cmarcum at uci.edu> wrote:
>> Hello,
>>
>> I am sure I am not the only person with this problem.
>>
>> I have a list with n elements, each consisting of a single column matrix
>> with different row lengths. Each row has a name ranging from A to E.
>> Here
>> is an example:
>>
>> alph[]
>> A 1
>> B 2
>> C 3
>> D 4
>>
>> alph[]
>> A 1
>> C 3
>> D 4
>>
>> alph[]
>> A 1
>> D 4
>> E 5
>>
>>
>> I would like to create a matrix from the elements in the list with n
>> columns such that the row names are preserved and NAs are inserted into
>> the cells where the uneven lists do not match up based on their row
>> names.
>> Here is an example of the desired output:
>>
>> newmatrix
>>  [,1]  [,2]  [,3]
>> A  1     1     1
>> B  2     NA    NA
>> C  3     3     NA
>> D  4     4     4
>> E  NA    NA    5
>>
>> Any suggestions?
>> I have tried
>> do.call("cbind",list)
>> I also thought I was on the right track when I tried converting each
>> element into a vector and then running this loop (which ultimately
>> failed):
>>
>> newmat<-matrix(NA,ncol=3,nrow=5)
>> colnames(newmatrix)<-c(A:E)
>> for(j in 1:3){
>> for(i in 1:5){
>> for(k in 1:length(list[[i]])){
>> if(is.na(match(colnames(newmatrix),names(alph[[i]])))[j]==TRUE){
>> newmatrix[i,j]<-NA}
>> else newmatrix[i,j]<-alph[[i]][k]}}}
>>
>> Thanks,
>> Chris
>> UCI Sociology
>>
>> ______________________________________________
>> R-help at stat.math.ethz.ch mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help