[Rd] Undocumented 'use.names' argument to c()

[Karl Millar]

I'd expect that a lot of the performance overhead could be eliminated
by simply improving the underlying code.  IMHO, we should ignore it in
deciding the API that we want here.

On Fri, Sep 23, 2016 at 10:54 AM, Henrik Bengtsson
<henrik.bengtsson at gmail.com> wrote:
> I'd vote for it to stay.  It could of course suprise someone who'd
> expect c(list(a=1), b=2, use.names = FALSE) to generate list(a=1, b=2,
> use.names=FALSE).   On the upside, is the performance gain from using
> use.names=FALSE.  Below benchmarks show that the combining of the
> names attributes themselves takes ~20-25 times longer than the
> combining of the integers themselves.  Also, at no surprise,
> use.names=FALSE avoids some memory allocations.
>
>> options(digits = 2)
>>
>> a <- b <- c <- d <- 1:1e4
>> names(c) <- c
>> names(d) <- d
>>
>> stats <- microbenchmark::microbenchmark(
> +   c(a, b, use.names=FALSE),
> +   c(c, d, use.names=FALSE),
> +   c(a, d, use.names=FALSE),
> +   c(a, b, use.names=TRUE),
> +   c(a, d, use.names=TRUE),
> +   c(c, d, use.names=TRUE),
> +   unit = "ms"
> + )
>>
>> stats
> Unit: milliseconds
>                        expr   min    lq  mean median    uq   max neval
>  c(a, b, use.names = FALSE) 0.031 0.032 0.049  0.034 0.036 1.474   100
>  c(c, d, use.names = FALSE) 0.031 0.031 0.035  0.034 0.035 0.064   100
>  c(a, d, use.names = FALSE) 0.031 0.031 0.049  0.034 0.035 1.452   100
>   c(a, b, use.names = TRUE) 0.031 0.031 0.055  0.034 0.036 2.094   100
>   c(a, d, use.names = TRUE) 0.510 0.526 0.588  0.549 0.617 1.998   100
>   c(c, d, use.names = TRUE) 0.780 0.815 0.886  0.841 0.944 1.430   100
>
>> profmem::profmem(c(c, d, use.names=FALSE))
> Rprofmem memory profiling of:
> c(c, d, use.names = FALSE)
>
> Memory allocations:
>       bytes      calls
> 1     80040 <internal>
> total 80040
>
>> profmem::profmem(c(c, d, use.names=TRUE))
> Rprofmem memory profiling of:
> c(c, d, use.names = TRUE)
>
> Memory allocations:
>        bytes      calls
> 1      80040 <internal>
> 2     160040 <internal>
> total 240080
>
> /Henrik
>
> On Fri, Sep 23, 2016 at 10:25 AM, William Dunlap via R-devel
> <r-devel at r-project.org> wrote:
>> In Splus c() and unlist() called the same C code, but with a different
>> 'sys_index'  code (the last argument to .Internal) and c() did not consider
>> an argument named 'use.names' special.
>>
>>> c
>> function(..., recursive = F)
>> .Internal(c(..., recursive = recursive), "S_unlist", TRUE, 1)
>>> unlist
>> function(data, recursive = T, use.names = T)
>> .Internal(unlist(data, recursive = recursive, use.names = use.names),
>> "S_unlist", TRUE, 2)
>>> c(A=1,B=2,use.names=FALSE)
>>  A B use.names
>>  1 2         0
>>
>> The C code used sys_index==2 to mean 'the last  argument is the 'use.names'
>> argument, if sys_index==1 only the recursive argument was considered
>> special.
>>
>> Sys.funs.c:
>>  405 S_unlist(vector *ent, vector *arglist, s_evaluator *S_evaluator)
>>  406 {
>>  407         int which = sys_index; boolean named, recursive, names;
>>  ...
>>  419         args = arglist->value.tree; n = arglist->length;
>>  ...
>>  424         names = which==2 ? logical_value(args[--n], ent, S_evaluator)
>> : (which == 1);
>>
>> Thus there is no historical reason for giving c() the use.names argument.
>>
>>
>> Bill Dunlap
>> TIBCO Software
>> wdunlap tibco.com
>>
>> On Fri, Sep 23, 2016 at 9:37 AM, Suharto Anggono Suharto Anggono via
>> R-devel <r-devel at r-project.org> wrote:
>>
>>> In S-PLUS 3.4 help on 'c' (http://www.uni-muenster.de/
>>> ZIV.BennoSueselbeck/s-html/helpfiles/c.html), there is no 'use.names'
>>> argument.
>>>
>>> Because 'c' is a generic function, I don't think that changing formal
>>> arguments is good.
>>>
>>> In R devel r71344, 'use.names' is not an argument of functions 'c.Date',
>>> 'c.POSIXct' and 'c.difftime'.
>>>
>>> Could 'use.names' be documented to be accepted by the default method of
>>> 'c', but not listed as a formal argument of 'c'? Or, could the code that
>>> handles the argument name 'use.names' be removed?
>>> ----------------
>>> >>>>> David Winsemius <dwinsemius at comcast.net>
>>> >>>>>     on Tue, 20 Sep 2016 23:46:48 -0700 writes:
>>>
>>>     >> On Sep 20, 2016, at 7:18 PM, Karl Millar via R-devel <r-devel at
>>> r-project.org> wrote:
>>>     >>
>>>     >> 'c' has an undocumented 'use.names' argument.  I'm not sure if this
>>> is
>>>     >> a documentation or implementation bug.
>>>
>>>     > It came up on stackoverflow a couple of years ago:
>>>
>>>     > http://stackoverflow.com/questions/24815572/why-does-
>>> function-c-accept-an-undocumented-argument/24815653#24815653
>>>
>>>     > At the time it appeared to me to be a documentation lag.
>>>
>>> Thank you, Karl and David,
>>> yes it is a documentation glitch ... and a bit more:  Experts know that
>>> print()ing of primitive functions is, eehm, "special".
>>>
>>> I've committed a change to R-devel ... (with the intent to port
>>> to R-patched).
>>>
>>> Martin
>>>
>>>     >>
>>>     >>> c(a = 1)
>>>     >> a
>>>     >> 1
>>>     >>> c(a = 1, use.names = F)
>>>     >> [1] 1
>>>     >>
>>>     >> Karl
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>
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>>
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