[Rd] dimnames incoherence?

[William Dunlap]

How far would you like to go with the automatic creation of dimnames in
nested replacement operations on arrays?  It currently works nicely with [<-
   > a <- array(numeric(), dim=c(2,0,1)); dimnames(a)[3] <- list("One")
   > str(a)
    num[1:2, 0 , 1]
    - attr(*, "dimnames")=List of 3
     ..$ : NULL
     ..$ : NULL
     ..$ : chr "One"

It works most of the time (except for length=1) for [[<-
  > a <- array(numeric(), dim=c(2,0,1)); dimnames(a)[[1]] <- c("X1","X2")
  > a <- array(numeric(), dim=c(2,0,1)); dimnames(a)[[2]] <- character()
  > a <- array(numeric(), dim=c(2,0,1)); dimnames(a)[[3]] <- "Z1"
  Error in dimnames(a)[[3]] <- "Z1" : 'dimnames' must be a list

It does not work at all for names<-.
> a <- array(numeric(), dim=c(2,0,1)); names(dimnames(a)) <- c("X","Y","Z")
Error in names(dimnames(a)) <- c("X", "Y", "Z") :
  attempt to set an attribute on NULL
> a <- array(numeric(), dim=c(2,0,1)); dimnames(a)<-vector("list",3);
names(dimnames(a)) <- c("X","Y","Z")
> str(a)
 num[1:2, 0 , 1]
 - attr(*, "dimnames")=List of 3
  ..$ X: NULL
  ..$ Y: NULL
  ..$ Z: NULL

Bill Dunlap
TIBCO Software
wdunlap tibco.com


On Wed, Feb 19, 2020 at 6:24 AM Serguei Sokol <sokol using insa-toulouse.fr>
wrote:

> Hi,
>
> I was bitten by a little incoherence in dimnames assignment or may be I
> missed some point.
> Here is the case. If I assign row names via dimnames(a)[[1]], when
> nrow(a)=1 then an error is thrown. But if I do the same when nrow(a) > 1
> it's OK. Is one of this case works unexpectedly? Both? Neither?
>
> a=as.matrix(1)
> dimnames(a)[[1]]="a" # error: 'dimnames' must be a list
>
> aa=as.matrix(1:2)
> dimnames(aa)[[1]]=c("a", "b") # OK
>
> In the second case, dimnames(aa) is not a list (like in the first case)
> but it works.
> I would expect that the both work or neither.
>
> Your thoughts are welcome.
> Best,
> Serguei.
>
> PS the same apply for dimnames(a)[[2]]<-.
>
>  > sessionInfo()
> R version 3.6.1 (2019-07-05)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Mageia 7
>
> Matrix products: default
> BLAS/LAPACK: /home/opt/OpenBLAS/lib/libopenblas_sandybridge-r0.3.6.so
>
> locale:
>   [1] LC_CTYPE=fr_FR.UTF-8       LC_NUMERIC=C
>   [3] LC_TIME=fr_FR.UTF-8        LC_COLLATE=fr_FR.UTF-8
>   [5] LC_MONETARY=fr_FR.UTF-8    LC_MESSAGES=fr_FR.UTF-8
>   [7] LC_PAPER=fr_FR.UTF-8       LC_NAME=C
>   [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=fr_FR.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] parallel  stats     graphics  grDevices utils     datasets methods
> [8] base
>
> other attached packages:
> [1] multbxxc_1.0.1            rmumps_5.2.1-11
> [3] arrApply_2.1              RcppArmadillo_0.9.800.4.0
> [5] Rcpp_1.0.3                slam_0.1-47
> [7] nnls_1.4
>
> loaded via a namespace (and not attached):
> [1] compiler_3.6.1   tools_3.6.1      codetools_0.2-16
>
> ______________________________________________
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>

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