R help - Dec 2005 - R is GNU S, not C.... [was "how to get or store ....."]

======= 2005-12-06 22:16:17 伳侜佋佢伬伌佇伵佒佇佇伌伒伬仯伜======
>Martin Maechler a 侀crit :
>
>> please, please,  these trailing ";"  are  *so* ugly.
>> This is GNU S, not C (or matlab) !
>> 
>> but I'll be happy already if you could
>> drop these ugly empty statements at the end of your lines...
>
>May I disagree ?
>I find missing ";" at end of lines *so* ugly.
>Ugly/not ugly depends on our observer's eyes.
> From my programmer point of view, I prefer to mark
>clearly the end of the lines.
>In many languages, it's safer to do it this way,
>and I thank the R developers to permit it.
>(in my opinion, it should even be mandatory).
>(By the way, marking the end of lines with a unique symbol
>makes also the job easier for the following treatment.)
>And yes, I'm also a C programmer ;-)
>
> > {and I have another chain of argments why   "<-" is so
more
> > expressive than "="
>
>Why "<-" seems better than "=" is also quite
mysterious for me.
>There was a discussion about this point recently I think.
>I believe in 99% of cases it's more for historical reason
>(and perhaps also for some "snob" reasons).
>
>I am not at all a 20 years experienced R programmer, but I have
>written several hundreds of R lines those 6 last months,
>and until today didn't get any problem using "=" instead of
"<-".
I think it is NOT just for historical reason.see the following
example:
> rm(x)
> mean(x=1:10)
[1] 5.5
> x
Error: object "x" not found
> mean(x<-1:10)
[1] 5.5
> x
 [1]  1  2  3  4  5  6  7  8  9 10
>But I'll read your chain of arguments with interest.
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
= = = = = = = = = = = = = = = = = = = 			


 

2005-12-06

------
Deparment of Sociology
Fudan University

My new mail addres is ronggui.huang at gmail.com
Blog:http://sociology.yculblog.com

> Jan T. Kim wrote:
>
> There is a draft R Coding Convention available at
> 
>     http://www.maths.lth.se/help/R/RCC/
> 
> which may be useful for finding a style that is good because it is
> widely used and therefore familiar to a large number of readers.-- 
However, as the author Henrik Bengtsson points out "these guidelines are
ours and not the R-developers." Perhaps a definitive style guide
published by R core that ensured consistency among new base code would
be a helpful addition. I personally find the above style guide extremely
useful when multiple programmers work on the same project, and would
welcome a formal endorsement or revision by the R developers. (And
despite Henrik's elegant guide, I too leave off the semicolons at the
end of the lines.)

--Robert

From: Martin Maechler
> 
> >>>>> "P" == P Ehlers <ehlers at
math.ucalgary.ca>
> >>>>>     on Tue, 06 Dec 2005 08:35:07 -0700 writes:
> 
>     P> vincent at 7d4.com wrote:
> 
>     >> Martin Maechler a ??crit :
>     >> 
>     >> 
>     >>> please, please,  these trailing ";"  are  *so*
ugly.
>     >>> This is GNU S, not C (or matlab) !
>     >>> 
>     >>> but I'll be happy already if you could
>     >>> drop these ugly empty statements at the end of your
lines...
>     >> 
>     >> 
>     >> May I disagree ?
>     >> I find missing ";" at end of lines *so* ugly.
>     >> Ugly/not ugly depends on our observer's eyes.
>     >> From my programmer point of view, I prefer to mark
>     >> clearly the end of the lines.
>     >> In many languages, it's safer to do it this way,
>     >> and I thank the R developers to permit it.
>     >> (in my opinion, it should even be mandatory).
>     >> (By the way, marking the end of lines with a unique symbol
>     >> makes also the job easier for the following treatment.)
>     >> And yes, I'm also a C programmer ;-)
>     >> 
>     >> > {and I have another chain of argments why  
"<-" is so more
>     >> > expressive than "="
>     >> 
>     >> Why "<-" seems better than "=" is also
quite mysterious for me.
>     >> There was a discussion about this point recently I think.
>     >> I believe in 99% of cases it's more for historical reason
>     >> (and perhaps also for some "snob" reasons).
>     >> 
>     >> I am not at all a 20 years experienced R programmer, but I
have
>     >> written several hundreds of R lines those 6 last months,
>     >> and until today didn't get any problem using "="
> instead of "<-".
>     >> 
>     >> But I'll read your chain of arguments with interest.
> 
> 
>     P> Well, I'll have to disagree a bit. While I don't care so
much
>     P> about trailing ";" (as long as it does not become
mandatory),
>     P> I don't like the use of "=" for assignment and
that's
> definitely
>     P> NOT for "snob" reasons, whatever those are. I just 
> think code is
>     P> *much* easier to read if assignment is distinguished from
>     P> argument settings.
> 
> Thank you, Peter.  Indeed, this is exactly the main of my arguments:
> Since "=" is used quite often in S for argument setting in
> function calls, *additionally* using "<-" for assignment is
> more expressive. 
> Also, e.g., a2ps (a nice 'ASCII' to PostScript converter), comes
> {at least on Debian Linux} preconfigured for R, and uses nice
> typesetting for "<-"; similarly for ESS.
> OTOH, it's pretty hard to correctly markup and differentiate
> those "=" which are assignments from those which are function.
> argument settings.
> 
>     P> Peter Ehlers
> 
> [But really, I'm more concerned and quite bit disappointed by
>  the diehard ";" lovers]
> 
> Martin Maechler
Matlab also allows both with and without ";", but I guess most people
learn
quickly what the preferred way is:  Without ";", Matlab prints the
output of
commands, including assignments; e.g., if you assign a 1e5-row matrix to
something, and didn't terminate the line with ";", Matlab will
print that
matrix to the console.

Personally, having the extraneous ";" doesn't bother me nearly as
much as
not indenting the code properly or leave spaces around operators.  I don't
use them, because I seldom have difficulty knowing when a statement is
suppose to end (given the code is properly indented).  Those who use Python
would know quite well, too, I guess.  For those who insist on having
";", I
guess they will never get the point of something like Python (or even
Fortran...).

Andy

ronggui a 仺仸crit :
> I think it is NOT just for historical reason.
> see the following example:
> 
>>rm(x)
>>mean(x=1:10)
> [1] 5.5
>>x
> Error: object "x" not found
x is an argument local to mean(),
did you expect another answer ?
>>mean(x<-1:10)
> [1] 5.5
>>x
>  [1]  1  2  3  4  5  6  7  8  9 10
What is the goal of this "example" ?

Here with "<-",
(voluntary, or not, side effect)
the global variable x is, also, created.
Did the writer really want that ???

I though there were other specific statements
especially intended for global assignment, eg "<<-".

If this example was intended to prove "<-"
is better than "="
... I'm not really convinced !

From: vincent at 7d4.com
> 
> ronggui a ??crit :
> 
> > I think it is NOT just for historical reason.
> > see the following example:
> > 
> >>rm(x)
> >>mean(x=1:10)
> > [1] 5.5
> >>x
> > Error: object "x" not found
> 
> x is an argument local to mean(),
> did you expect another answer ?
> 
> >>mean(x<-1:10)
> > [1] 5.5
> >>x
> >  [1]  1  2  3  4  5  6  7  8  9 10
> 
> What is the goal of this "example" ?
I believe it's to show why "<-" is to be preferred over
"=" for
assignment...
 
> Here with "<-",
> (voluntary, or not, side effect)
> the global variable x is, also, created.
> Did the writer really want that ???
Very much so, I believe.
 
> I though there were other specific statements
> especially intended for global assignment, eg "<<-".
You need to distinguish assignment in function _call_ and assignment in
function _definition_.  They ain't the same.
 
> If this example was intended to prove "<-"
> is better than "="
> ... I'm not really convinced !
In that case, let's try another one (which is one big reason I stopped using
"=" for assignment):

> long.comp <- function(n) {
+     Sys.sleep(n)
+     n
+ }
> result = long.comp(30)
> system.time(result = long.comp(30))
Error in system.time(result = long.comp(30)) : 
	unused argument(s) (result ...)
> system.time(result <- long.comp(30))
[1]  0.00  0.00 30.05    NA    NA
> str(result)
 num 30

Cheers,
Andy
 
>

_______________________________________________________________________________________


Hm, a style war on R-Help. I wonder if this goes for long enough, we'll come
to the question of where to put the braces. ;)

Personally, I always use <- instead of = where applicable. In addition to the
distinction between assignment and naming arguments in function calls, it helps
avoid the notorious =/== bug from C programming. Compare

    "if(x == 1) {..." /* comparison -- probably what was wanted */

with

    "if(x = 1) {..."  /* oops */

This has bitten me a number of times in C, so I'd like to avoid it in R/S.
Using "if(identical(x, 1)) {..." also addresses this problem, but that
just looks awkward to me.


-- 
Hong Ooi
Senior Research Analyst, IAG Limited
388 George St, Sydney NSW 2000
+61 (2) 9292 1566

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at
stat.math.ethz.ch] On Behalf Of Liaw, Andy
Sent: Wednesday, 7 December 2005 7:17 AM
To: 'vincent at 7d4.com'; r-help at stat.math.ethz.ch
Subject: Re: [R] R is GNU S, not C.... [was "how to get or store
....."]

From: vincent at 7d4.com
> 
> ronggui a ??crit :
> 
> > I think it is NOT just for historical reason.
> > see the following example:
> > 
> >>rm(x)
> >>mean(x=1:10)
> > [1] 5.5
> >>x
> > Error: object "x" not found
> 
> x is an argument local to mean(),
> did you expect another answer ?
> 
> >>mean(x<-1:10)
> > [1] 5.5
> >>x
> >  [1]  1  2  3  4  5  6  7  8  9 10
> 
> What is the goal of this "example" ?
I believe it's to show why "<-" is to be preferred over
"=" for
assignment...
 
> Here with "<-",
> (voluntary, or not, side effect)
> the global variable x is, also, created.
> Did the writer really want that ???
Very much so, I believe.
 
> I though there were other specific statements
> especially intended for global assignment, eg "<<-".
You need to distinguish assignment in function _call_ and assignment in
function _definition_.  They ain't the same.
 
> If this example was intended to prove "<-"
> is better than "="
> ... I'm not really convinced !
In that case, let's try another one (which is one big reason I stopped using
"=" for assignment):

> long.comp <- function(n) {
+     Sys.sleep(n)
+     n
+ }
> result = long.comp(30)
> system.time(result = long.comp(30))
Error in system.time(result = long.comp(30)) : 
	unused argument(s) (result ...)
> system.time(result <- long.comp(30))
[1]  0.00  0.00 30.05    NA    NA
> str(result)
 num 30

Cheers,
Andy
 
>
______________________________________________
R-help at stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html



_______________________________________________________________________________________

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======= 2005-12-07 04:17:03 伳侜佋佢伬伌佇伵佒佇佇伌伒伬仯伜======
>From: vincent at 7d4.com
>> 
>> ronggui a 侀crit :
>> 
>> > I think it is NOT just for historical reason.
>> > see the following example:
>> > 
>> >>rm(x)
>> >>mean(x=1:10)
>> > [1] 5.5
>> >>x
>> > Error: object "x" not found
>> 
>> x is an argument local to mean(),
>> did you expect another answer ?
>> 
>> >>mean(x<-1:10)
>> > [1] 5.5
>> >>x
>> >  [1]  1  2  3  4  5  6  7  8  9 10
>> 
>> What is the goal of this "example" ?
>
>I believe it's to show why "<-" is to be preferred over
"=" for
>assignment...
Yeah,I want to show "<-" is to be preferred.
Sorry for not making it clearly.
>> Here with "<-",
>> (voluntary, or not, side effect)
>> the global variable x is, also, created.
>> Did the writer really want that ???
>
>Very much so, I believe.
> 
>> I though there were other specific statements
>> especially intended for global assignment, eg "<<-".
>
>You need to distinguish assignment in function _call_ and assignment in
>function _definition_.  They ain't the same.
> 
>> If this example was intended to prove "<-"
>> is better than "="
>> ... I'm not really convinced !
>
>In that case, let's try another one (which is one big reason I stopped
using
>"=" for assignment):
>
>
>> long.comp <- function(n) {
>+     Sys.sleep(n)
>+     n
>+ }
>> result = long.comp(30)
>> system.time(result = long.comp(30))
>Error in system.time(result = long.comp(30)) : 
>	unused argument(s) (result ...)
>> system.time(result <- long.comp(30))
>[1]  0.00  0.00 30.05    NA    NA
>> str(result)
> num 30
>
>Cheers,
>Andy
> 
>>
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
= = = = = = = = = = = = = = = = = = = 			


 

2005-12-07

------
Deparment of Sociology
Fudan University

My new mail addres is ronggui.huang at gmail.com
Blog:http://sociology.yculblog.com

I think "<-" is better than "=" in some cases.

======= 2005-12-07 08:51:30 Write仯伜======
>
>
>======= 2005-12-07 04:17:03 伳侜佋佢伬伌佇伵佒佇佇伌伒伬仯伜======>
>>From: vincent at 7d4.com
>>> 
>>> ronggui a 侀crit :
>>> 
>>> > I think it is NOT just for historical reason.
>>> > see the following example:
>>> > 
>>> >>rm(x)
>>> >>mean(x=1:10)
>>> > [1] 5.5
>>> >>x
>>> > Error: object "x" not found
>>> 
>>> x is an argument local to mean(),
>>> did you expect another answer ?
>>> 
>>> >>mean(x<-1:10)
>>> > [1] 5.5
>>> >>x
>>> >  [1]  1  2  3  4  5  6  7  8  9 10
>>> 
>>> What is the goal of this "example" ?
>>
>>I believe it's to show why "<-" is to be preferred over
"=" for
>>assignment...
>
>Yeah,I want to show "<-" is to be preferred.
>Sorry for not making it clearly.
>
>>> Here with "<-",
>>> (voluntary, or not, side effect)
>>> the global variable x is, also, created.
>>> Did the writer really want that ???
>>
>>Very much so, I believe.
>> 
>>> I though there were other specific statements
>>> especially intended for global assignment, eg
"<<-".
>>
>>You need to distinguish assignment in function _call_ and assignment in
>>function _definition_.  They ain't the same.
>> 
>>> If this example was intended to prove "<-"
>>> is better than "="
>>> ... I'm not really convinced !
>>
>>In that case, let's try another one (which is one big reason I
stopped using
>>"=" for assignment):
>>
>>
>>> long.comp <- function(n) {
>>+     Sys.sleep(n)
>>+     n
>>+ }
>>> result = long.comp(30)
>>> system.time(result = long.comp(30))
>>Error in system.time(result = long.comp(30)) : 
>>	unused argument(s) (result ...)
>>> system.time(result <- long.comp(30))
>>[1]  0.00  0.00 30.05    NA    NA
>>> str(result)
>> num 30
>>
>>Cheers,
>>Andy
>> 
>>>
>>
>>______________________________________________
>>R-help at stat.math.ethz.ch mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-help
>>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>
>= = = = = = = = = = = = = = = = = = = >			
>
>
> 
>
>2005-12-07
>
>------
>Deparment of Sociology
>Fudan University
>
>My new mail addres is ronggui.huang at gmail.com
>Blog:http://sociology.yculblog.com
>
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
= = = = = = = = = = = = = = = = = = = 				 
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仭仭仭仭仭仭仭仭仭仭仭仭仭仭仭仭guangxing at ict.ac.cn
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