[Rd] Small bug in the documentation of `[.data.frame`

[Martin Maechler]

>>>>> 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 using r-project.org mailing list
    >> https://stat.ethz.ch/mailman/listinfo/r-devel
    >> 

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