R devel - Nov 2018 - Subsetting row in single column matrix drops names in resulting vector

Hi Rui. Thanks for answer, I'm aware of drop = FALSE option. Unfortunately
it doesn't resolve the issue - I'm expecting to get a vector, not a
matrix .

??, 21 ????. 2018 ?. ? 20:54, Rui Barradas <ruipbarradas at sapo.pt>:
> Hello,
>
> Use drop = FALSE.
>
> a[1, , drop = FALSE]
> #     col1
> #row1    1
>
>
> Hope this helps,
>
> Rui Barradas
>
> ?s 16:51 de 21/11/2018, Dmitriy Selivanov escreveu:
> > Hello here. I'm struggling to understand R's subsetting
behavior in
> couple
> > of edge cases - subsetting row in a single column matrix and
subsetting
> > column in a single row matrix. I've read R's docs several
times and
> haven't
> > found answer.
> >
> > Consider following example:
> >
> > a = matrix(1:2, nrow = 2, dimnames = list(c("row1",
"row2"), c("col1")))
> > a[1, ]
> > # 1
> >
> > It returns *unnamed* vector `1` where I would expect named vector. In
> fact
> > it returns named vector when number of columns is > 1.
> > Same issue applicable to single row matrix. Is it a bug? looks very
> > counterintuitive.
> >
> >
>

-- 
Regards
Dmitriy Selivanov

	[[alternative HTML version deleted]]

The problem is that the drop is only applied (or not) after the subsetting, so
what R does is:
- Getting the subset, which means a 1 x 1 matrix.
- Only then It either returns that as is (when drop=FALSE), or removes ALL
dimensions of extent 1, regardless of whether these are rows or columns (or
higher dimensions).
And it can't keep any names, because what name should be returned? The name
'row1' is just as valid as 'col1'.
I guess if we could design everything anew, a solution would be to be able to
specify something like a[1,,drop='row'], or a[1,,drop=1] to drop the
rows but keep columns, and get a vector being equal to 'row1' (which in
this case just has length-1, and names 'col1')
That not how it's designed, but you could use 'adrop()' from the
'abind' package:
abind:: adrop(a[1,,drop=FALSE], drop=1) first subsets, then drops the
row-dimension, so gives what you're looking for.
Hope this solves your problem.

Best regards, 
Emil Bode
 

?On 21/11/2018, 17:58, "R-devel on behalf of Dmitriy Selivanov"
<r-devel-bounces at r-project.org on behalf of selivanov.dmitriy at
gmail.com> wrote:

    Hi Rui. Thanks for answer, I'm aware of drop = FALSE option.
Unfortunately
    it doesn't resolve the issue - I'm expecting to get a vector, not a
matrix .
    
    ??, 21 ????. 2018 ?. ? 20:54, Rui Barradas <ruipbarradas at sapo.pt>:
    
    > Hello,
    >
    > Use drop = FALSE.
    >
    > a[1, , drop = FALSE]
    > #     col1
    > #row1    1
    >
    >
    > Hope this helps,
    >
    > Rui Barradas
    >
    > ?s 16:51 de 21/11/2018, Dmitriy Selivanov escreveu:
    > > Hello here. I'm struggling to understand R's subsetting
behavior in
    > couple
    > > of edge cases - subsetting row in a single column matrix and
subsetting
    > > column in a single row matrix. I've read R's docs several
times and
    > haven't
    > > found answer.
    > >
    > > Consider following example:
    > >
    > > a = matrix(1:2, nrow = 2, dimnames = list(c("row1",
"row2"), c("col1")))
    > > a[1, ]
    > > # 1
    > >
    > > It returns *unnamed* vector `1` where I would expect named vector.
In
    > fact
    > > it returns named vector when number of columns is > 1.
    > > Same issue applicable to single row matrix. Is it a bug? looks
very
    > > counterintuitive.
    > >
    > >
    >
    
    
    -- 
    Regards
    Dmitriy Selivanov
    
    	[[alternative HTML version deleted]]
    
    ______________________________________________
    R-devel at r-project.org mailing list
    https://stat.ethz.ch/mailman/listinfo/r-devel

Le 22/11/2018 ? 14:47, Emil Bode a ?crit?:
> The problem is that the drop is only applied (or not) after the subsetting,
so what R does is:
> - Getting the subset, which means a 1 x 1 matrix.
> - Only then It either returns that as is (when drop=FALSE), or removes ALL
dimensions of extent 1, regardless of whether these are rows or columns (or
higher dimensions).
> And it can't keep any names, because what name should be returned? The
name 'row1' is just as valid as 'col1'.
If it is the only reason to not return any name in this case, I could 
make a suggestion.
Let return the name corresponding to the index in subsetting request, 
i.e. for a one-column matrix example it would give

names(a[1,])
#"row1"
names(a[2,])
#"row2"

as the indexes 1 and 2 here above corresponds to rows.

Just my 0.02?
Serguei.

> I guess if we could design everything anew, a solution would be to be able
to specify something like a[1,,drop='row'], or a[1,,drop=1] to drop the
rows but keep columns, and get a vector being equal to 'row1' (which in
this case just has length-1, and names 'col1')
> That not how it's designed, but you could use 'adrop()' from
the 'abind' package:
> abind:: adrop(a[1,,drop=FALSE], drop=1) first subsets, then drops the
row-dimension, so gives what you're looking for.
> Hope this solves your problem.
>
> Best regards,
> Emil Bode
>   
>
> ?On 21/11/2018, 17:58, "R-devel on behalf of Dmitriy Selivanov"
<r-devel-bounces at r-project.org on behalf of selivanov.dmitriy at
gmail.com> wrote:
>
>      Hi Rui. Thanks for answer, I'm aware of drop = FALSE option.
Unfortunately
>      it doesn't resolve the issue - I'm expecting to get a vector,
not a matrix .
>      
>      ??, 21 ????. 2018 ?. ? 20:54, Rui Barradas <ruipbarradas at
sapo.pt>:
>      
>      > Hello,
>      >
>      > Use drop = FALSE.
>      >
>      > a[1, , drop = FALSE]
>      > #     col1
>      > #row1    1
>      >
>      >
>      > Hope this helps,
>      >
>      > Rui Barradas
>      >
>      > ?s 16:51 de 21/11/2018, Dmitriy Selivanov escreveu:
>      > > Hello here. I'm struggling to understand R's
subsetting behavior in
>      > couple
>      > > of edge cases - subsetting row in a single column matrix and
subsetting
>      > > column in a single row matrix. I've read R's docs
several times and
>      > haven't
>      > > found answer.
>      > >
>      > > Consider following example:
>      > >
>      > > a = matrix(1:2, nrow = 2, dimnames =
list(c("row1", "row2"), c("col1")))
>      > > a[1, ]
>      > > # 1
>      > >
>      > > It returns *unnamed* vector `1` where I would expect named
vector. In
>      > fact
>      > > it returns named vector when number of columns is > 1.
>      > > Same issue applicable to single row matrix. Is it a bug?
looks very
>      > > counterintuitive.
>      > >
>      > >
>      >
>      
>      
>      --
>      Regards
>      Dmitriy Selivanov
>      
>      	[[alternative HTML version deleted]]
>      
>      ______________________________________________
>      R-devel at r-project.org mailing list
>      https://stat.ethz.ch/mailman/listinfo/r-devel
>      
>
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

-- 
Serguei Sokol
Ingenieur de recherche INRA

Cellule math?matiques
LISBP, INSA/INRA UMR 792, INSA/CNRS UMR 5504
135 Avenue de Rangueil
31077 Toulouse Cedex 04

tel: +33 5 62 25 01 27
email: sokol at insa-toulouse.fr
http://www.lisbp.fr

Emil, thanks for very nice explanation. Wish base drop would have same
behavior as abind::adrop.

??, 22 ????. 2018 ?., 17:47 Emil Bode emil.bode at dans.knaw.nl:
> The problem is that the drop is only applied (or not) after the
> subsetting, so what R does is:
> - Getting the subset, which means a 1 x 1 matrix.
> - Only then It either returns that as is (when drop=FALSE), or removes ALL
> dimensions of extent 1, regardless of whether these are rows or columns (or
> higher dimensions).
> And it can't keep any names, because what name should be returned? The
> name 'row1' is just as valid as 'col1'.
> I guess if we could design everything anew, a solution would be to be able
> to specify something like a[1,,drop='row'], or a[1,,drop=1] to drop
the
> rows but keep columns, and get a vector being equal to 'row1'
(which in
> this case just has length-1, and names 'col1')
> That not how it's designed, but you could use 'adrop()' from
the 'abind'
> package:
> abind:: adrop(a[1,,drop=FALSE], drop=1) first subsets, then drops the
> row-dimension, so gives what you're looking for.
> Hope this solves your problem.
>
> Best regards,
> Emil Bode
>
>
> ?On 21/11/2018, 17:58, "R-devel on behalf of Dmitriy Selivanov"
<
> r-devel-bounces at r-project.org on behalf of selivanov.dmitriy at
gmail.com>
> wrote:
>
>     Hi Rui. Thanks for answer, I'm aware of drop = FALSE option.
> Unfortunately
>     it doesn't resolve the issue - I'm expecting to get a vector,
not a
> matrix .
>
>     ??, 21 ????. 2018 ?. ? 20:54, Rui Barradas <ruipbarradas at
sapo.pt>:
>
>     > Hello,
>     >
>     > Use drop = FALSE.
>     >
>     > a[1, , drop = FALSE]
>     > #     col1
>     > #row1    1
>     >
>     >
>     > Hope this helps,
>     >
>     > Rui Barradas
>     >
>     > ?s 16:51 de 21/11/2018, Dmitriy Selivanov escreveu:
>     > > Hello here. I'm struggling to understand R's
subsetting behavior in
>     > couple
>     > > of edge cases - subsetting row in a single column matrix and
> subsetting
>     > > column in a single row matrix. I've read R's docs
several times and
>     > haven't
>     > > found answer.
>     > >
>     > > Consider following example:
>     > >
>     > > a = matrix(1:2, nrow = 2, dimnames = list(c("row1",
"row2"),
> c("col1")))
>     > > a[1, ]
>     > > # 1
>     > >
>     > > It returns *unnamed* vector `1` where I would expect named
vector.
> In
>     > fact
>     > > it returns named vector when number of columns is > 1.
>     > > Same issue applicable to single row matrix. Is it a bug?
looks very
>     > > counterintuitive.
>     > >
>     > >
>     >
>
>
>     --
>     Regards
>     Dmitriy Selivanov
>
>         [[alternative HTML version deleted]]
>
>     ______________________________________________
>     R-devel at r-project.org mailing list
>     https://stat.ethz.ch/mailman/listinfo/r-devel
>
>
	[[alternative HTML version deleted]]