[Rd] dimnames incoherence?

[Martin Maechler]

>>>>> Serguei Sokol 
>>>>>     on Wed, 19 Feb 2020 15:21:21 +0100 writes:

    > 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.

I agree (even though I'm strongly advising people to use '<-'
  	instead of '=');
which in this case helps you get the name of the function really
involved:  It is  `dimnames<-`  (which is implemented in C
entirely, for matrices and other arrays).


    > Your thoughts are welcome.

I think we'd be happy if you report this formally on R's
bugzilla - https://bugs.r-project.org/ - as a bug.

  --> https://www.r-project.org/bugs.html

>From reading bugs.html you note that you should ask for an account there;
as I'm one of the people who get such request by e-mail, in this
case, I can do it directly (if you confirm you'd want in a
private e-mail).

    > Best,
    > Serguei.

    > PS the same apply for dimnames(a)[[2]]<-.

(of course)

NB *and*  importantly, the buglet is still in current versions of R 

Best,
Martin

    >> 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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