[R] The L Word

[Claudia Beleites]

On 02/24/2011 11:20 AM, Prof Brian Ripley wrote:
> On Thu, 24 Feb 2011, Tal Galili wrote:
>
>> Thank you all for the answers.
>>
>> So if I may extend on the question -
>> When is it important to use 'Literal integer'?
>> Under what situations could not using it cause problems?
>> Is it a matter of efficiency or precision or both?
>
> Efficiency: it avoids unnecessary type conversions. For example
>
> length(x) > 1
>
> has to coerce the lhs to double. We have converted the base code to use integer
> constants because such small efficiency gains can add up.
>
> Integer vectors can be stored more compactly than doubles, but that is not going
> to help for length 1:
>
>> object.size(1)
> 48 bytes
>> object.size(1L)
> 48 bytes
> (32-bit system).
see:
n <- 0L : 100L
szi <- sapply (n, function (n) object.size (integer (n)))
szd <- sapply (n, function (n) object.size (double (n)))
plot (n, szd)
points (n, szi, col = "red")




>
>>
>> Thanks,
>> Tal
>>
>>
>>
>>
>> ----------------Contact
>> Details:-------------------------------------------------------
>> Contact me: Tal.Galili at gmail.com | 972-52-7275845
>> Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) |
>> www.r-statistics.com (English)
>> ----------------------------------------------------------------------------------------------
>>
>>
>>
>>
>>
>> On Wed, Feb 23, 2011 at 6:15 PM, Tsjerk Wassenaar <tsjerkw at gmail.com> wrote:
>>
>>> Hi Gene,
>>>
>>> It means 'Literal integer'.
>>> So 1L is a proper integer 1, and 0L is a proper integer 0.
>>>
>>> Hope it helps,
>>>
>>> Tsjerk
>>>
>>> On Wed, Feb 23, 2011 at 5:08 PM, Gene Leynes <gleynes+r at gmail.com> wrote:
>>>> I've been wondering what L means in the R computing context, and was
>>>> wondering if someone could point me to a reference where I could read
>>> about
>>>> it, or tell me what it's called so that I can search for it myself. (L
>>> by
>>>> itself is a little too general for a search term).
>>>>
>>>> I encounter it in strange places, most recently in the "save"
>>> documentation.
>>>>
>>>> save(..., list = character(0L),
>>>>> file = stop("'file' must be specified"),
>>>>> ascii = FALSE, version = NULL, envir = parent.frame(),
>>>>> compress = !ascii, compression_level,
>>>>> eval.promises = TRUE, precheck = TRUE)
>>>>>
>>>>
>>>> I remember that you can also find it when you step inside an apply
>>> function:
>>>>
>>>>> sapply(1:10, function(x)browser())
>>>>> Called from: FUN(1:10[[1L]], ...)
>>>>>
>>>>
>>>> I apologize for being vague, it's just something that I would like to
>>>> understand about the R language (the R word).
>>>>
>>>> Thank you!
>>>>
>>>> Gene
>>>>
>>>> [[alternative HTML version deleted]]
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>>
>>>
>>> --
>>> Tsjerk A. Wassenaar, Ph.D.
>>>
>>> post-doctoral researcher
>>> Molecular Dynamics Group
>>> * Groningen Institute for Biomolecular Research and Biotechnology
>>> * Zernike Institute for Advanced Materials
>>> University of Groningen
>>> The Netherlands
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>


-- 
Claudia Beleites
Dipartimento dei Materiali e delle Risorse Naturali
Università degli Studi di Trieste
Via Alfonso Valerio 6/a
I-34127 Trieste

phone: +39 0 40 5 58-37 68
email: cbeleites at units.it