[Rd] precedence (was 'historical NA question')

[Hervé Pagès]

On 05/07/2014 12:52 PM, Simon Urbanek wrote:
> On May 7, 2014, at 3:37 PM, Hervé Pagès <hpages at fhcrc.org> wrote:
>
>> No big deal. These things can be tricky:
>>
>> https://stat.ethz.ch/pipermail/r-devel/2006-January/036022.html
>>
>> Sorry I couldn't resist ;-)
>>
>
> Yeah, but that's just yet another trip down the rabbit hole - why is -2 parsed as `-`(2) and not a single constant?

You wouldn't want -2 to be parsed as a single constant exactly for
the reason that you wouldn't want -2^2 to return 4. Having -2^2 treated
the same way as -x^2 is a sane feature.

> Is there a way to express a negative constant in R? Hmm…

Maybe some people have some use cases for this (speed ?).
Personally I don't. Of course it would require a special syntax,
something that would probably be as ugly and confusing as the
L suffix used for integer constants (L means long int in C).

H.

>
>
>> On 05/07/2014 09:16 AM, John Chambers wrote:
>>> On 5/7/14, 5:21 AM, Therneau, Terry M., Ph.D. wrote:
>>>> Hadley asked about the Blue book; my shelf still has the earlier brown
>>>> book
>>>>     Becker and Chambers, 1984, S: An interactive environment for data
>>>> analysis and graphics.
>>>
>>> Historically interesting, but there was never a guarantee that Version 3
>>> of S (the "blue book") was back-compatible with earlier versions.  We
>>> gave users some help in "getting on the road" to converting, that was
>>> all (see Appendix 4 to the blue book).
>>>
>>> For that one brief moment, we felt free to innovate.
>>>
>>> John
>>>
>>>>
>>>> The manual page for precedence is
>>>>
>>>> $               component select
>>>> %x              special operator
>>>> -               unary minus
>>>> :               sequence operator
>>>> ^ **            exponentiation
>>>> * /             mult/div
>>>> + -             add/sub
>>>> < > <= >= == != logical
>>>> !               not
>>>> & |             and/or
>>>> <- ->           assignment
>>>>
>>>> Terry Therneau
>>>>
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>>>
>>> ______________________________________________
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>>
>> --
>> Hervé Pagès
>>
>> Program in Computational Biology
>> Division of Public Health Sciences
>> Fred Hutchinson Cancer Research Center
>> 1100 Fairview Ave. N, M1-B514
>> P.O. Box 19024
>> Seattle, WA 98109-1024
>>
>> E-mail: hpages at fhcrc.org
>> Phone:  (206) 667-5791
>> Fax:    (206) 667-1319
>>
>> ______________________________________________
>> R-devel at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>

-- 
Hervé Pagès

Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024

E-mail: hpages at fhcrc.org
Phone:  (206) 667-5791
Fax:    (206) 667-1319