R devel - Dec 2020 - Small bug in the documentation of `[.data.frame`

On 29/12/2020 8:29 a.m., Rui Barradas wrote:
> Hello,
> 
> R 4.0.3 on Ubuntu 20.10, session info at end.
> 
> Isn't the default value of argument drop missing in
> 
> ?`[.data.frame`
> 
> Usage:
> 
>        ## S3 method for class 'data.frame'
>        x[i, j, drop = ]
> 
> 
> I had the impression that it was TRUE (it is when running the function,
> I'm talking about the docs).
No, you can see it if you print `[.data.frame`:

 > `[.data.frame`
function (x, i, j, drop = if (missing(i)) TRUE else length(cols) =     1)

So if you ask for specific rows and your dataframe has more than one 
column, it defaults to FALSE.

I think the Rd checks allow you to leave out defaults, but don't allow 
you to state them incorrectly, so that's probably why it is left as 
blank in the Usage section, and explained in the Arguments section.

Duncan Murdoch

> 
> 
> 
> sessionInfo()
> R version 4.0.3 (2020-10-10)
> Platform: x86_64-pc-linux-gnu (64-bit)
> Running under: Ubuntu 20.04.1 LTS
> 
> Matrix products: default
> BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0
> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0
> 
> locale:
>    [1] LC_CTYPE=pt_PT.UTF-8       LC_NUMERIC=C
>    [3] LC_TIME=pt_PT.UTF-8        LC_COLLATE=pt_PT.UTF-8
>    [5] LC_MONETARY=pt_PT.UTF-8    LC_MESSAGES=pt_PT.UTF-8
>    [7] LC_PAPER=pt_PT.UTF-8       LC_NAME=C
>    [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=pt_PT.UTF-8 LC_IDENTIFICATION=C
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
> loaded via a namespace (and not attached):
> [1] compiler_4.0.3 tools_4.0.3
> 
> 
> Happy holidays,
> 
> Rui Barradas
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

>>>>> Duncan Murdoch 
>>>>>     on Tue, 29 Dec 2020 08:37:51 -0500 writes:
    > On 29/12/2020 8:29 a.m., Rui Barradas wrote:
    >> Hello,
    >> 
    >> R 4.0.3 on Ubuntu 20.10, session info at end.
    >> 
    >> Isn't the default value of argument drop missing in
    >> 
    >> ?`[.data.frame`
    >> 
    >> Usage:
    >> 
    >> ## S3 method for class 'data.frame'
    >> x[i, j, drop = ]
    >> 
    >> 
    >> I had the impression that it was TRUE (it is when running the
function,
    >> I'm talking about the docs).

    > No, you can see it if you print `[.data.frame`:

    >> `[.data.frame`
    > function (x, i, j, drop = if (missing(i)) TRUE else length(cols) =   
> 1)

    > So if you ask for specific rows and your dataframe has more than one 
    > column, it defaults to FALSE.

    > I think the Rd checks allow you to leave out defaults, but don't
allow
    > you to state them incorrectly, so that's probably why it is left as
    > blank in the Usage section, and explained in the Arguments section.

    > Duncan Murdoch

Yes, indeed, Duncan,  it is as you think (above).

It is "official" in the sense that we've used this for a long
time in order to keep the 'Usage' section cleaner, when some
defaults are sophisticated, and a help page reader should rather
read the corresponding argument description.

Martin


    >> sessionInfo()
    >> R version 4.0.3 (2020-10-10)
    >> Platform: x86_64-pc-linux-gnu (64-bit)
    >> Running under: Ubuntu 20.04.1 LTS
    >> 
    >> Matrix products: default
    >> BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0
    >> LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0
    >> 
    >> locale:
    >> [1] LC_CTYPE=pt_PT.UTF-8       LC_NUMERIC=C
    >> [3] LC_TIME=pt_PT.UTF-8        LC_COLLATE=pt_PT.UTF-8
    >> [5] LC_MONETARY=pt_PT.UTF-8    LC_MESSAGES=pt_PT.UTF-8
    >> [7] LC_PAPER=pt_PT.UTF-8       LC_NAME=C
    >> [9] LC_ADDRESS=C               LC_TELEPHONE=C
    >> [11] LC_MEASUREMENT=pt_PT.UTF-8 LC_IDENTIFICATION=C
    >> 
    >> attached base packages:
    >> [1] stats     graphics  grDevices utils     datasets  methods  
base
    >> 
    >> loaded via a namespace (and not attached):
    >> [1] compiler_4.0.3 tools_4.0.3
    >> 
    >> 
    >> Happy holidays,
    >> 
    >> Rui Barradas
    >> 
    >> ______________________________________________
    >> 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