R help - Nov 2009 - Where are usages like "== 2L" documented?

Gurus:

I keep seeing other people?s code that contain ideas like

If (x == 2L)
X[-1L]
X - 1L

I have some idea of what?s going on, but where is the use of concepts like
?2L? documented?

Thanks, Bryan
*************
Bryan Hanson
Acting Chair
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA

On Nov 16, 2009, at 6:22 PM, Bryan Hanson wrote:
> Gurus:
>
> I keep seeing other people?s code that contain ideas like
>
> If (x == 2L)
> X[-1L]
> X - 1L
>
> I have some idea of what?s going on, but where is the use of  
> concepts like
> ?2L? documented?
Not sure where exactly, and it would depend on where you learned R.  
The integer data type information and notation should have been found  
among the material where you learned about "numeric",
"character",
"logical", .... that sort of basic notion.

-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

Bryan Hanson wrote:
> Gurus:
>
> I keep seeing other people?s code that contain ideas like
>
> If (x == 2L)
> X[-1L]
> X - 1L
>
> I have some idea of what?s going on, but where is the use of concepts like
> ?2L? documented?
>   
In the R Language Definition manual.  In this case, look in section 
3.1.1, "Constants".

Duncan Murdoch
> Thanks, Bryan
> *************
> Bryan Hanson
> Acting Chair
> Professor of Chemistry & Biochemistry
> DePauw University, Greencastle IN USA
>
> ______________________________________________
> 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.
>

?NumericConstants

will bring up a help page that mentions 

"All other numeric constants start with a digit or period and are either a
decimal or hexadecimal constant optionally followed by L."

and

"An numeric constant immediately followed by L is regarded as an integer
number when possible (and with a warning if it contains a "."). "

but I haven't found discussion of it anywhere else in the help pages.
Others may know what other help pages discuss this.

I'm surprised that the help page invoked from
?integer
does not discuss this.  Anyone know why not?

Best
Steve McKinney



> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Bryan Hanson
> Sent: Monday, November 16, 2009 3:23 PM
> To: R Help
> Subject: [R] Where are usages like "== 2L" documented?
> 
> Gurus:
> 
> I keep seeing other people?s code that contain ideas like
> 
> If (x == 2L)
> X[-1L]
> X - 1L
> 
> I have some idea of what?s going on, but where is the use of concepts
> like
> ?2L? documented?
> 
> Thanks, Bryan
> *************
> Bryan Hanson
> Acting Chair
> Professor of Chemistry & Biochemistry
> DePauw University, Greencastle IN USA
> 
> ______________________________________________
> 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.

Patrick reminded me that it's also in The R Inferno, another document that I
need to read again.

So now, a more particular semi-question:

x <- 1L
y <- 1
z <- 1.0

class(x) # integer
class(y) # numeric
class(z) # numeric

x == 1
x == 1L
y == 1
z == 1 # all test TRUE

Just to clarify, I think the steps above prove it, but *in a test* like x =1 the
test is for the contents, not the storage mode, not for a combination
of storage mode and contents.

So... The reason for defining the notion of "L" is smaller storage
space,
and more generally, for use anytime one wants explictly an integer for
whatever reason?  Are there other reasons, for instance, ways it saves lines
of code?

Bryan
*************
Bryan Hanson
Acting Chair
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA



On 11/17/09 4:20 AM, "Patrick Burns" <pburns at
pburns.seanet.com> wrote:
> 'The R Inferno' page 75.
> 
> 
> 
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of "The R Inferno" and "A Guide for the Unwilling S
User")
> 
> Bryan Hanson wrote:
>> Gurus:
>> 
>> I keep seeing other people?s code that contain ideas like
>> 
>> If (x == 2L)
>> X[-1L]
>> X - 1L
>> 
>> I have some idea of what?s going on, but where is the use of concepts
like
>> ?2L? documented?
>> 
>> Thanks, Bryan
>> *************
>> Bryan Hanson
>> Acting Chair
>> Professor of Chemistry & Biochemistry
>> DePauw University, Greencastle IN USA
>> 
>> ______________________________________________
>> 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.
>>