R devel - Nov 2006 - rm() deletes 'c' if c('a','b') is the argument (PR#9399)

Full_Name: Lixin Han
Version: 2.4.0
OS: Windows 2000
Submission from: (NULL) (155.94.110.222)


A character vector c('a','b') is supplied to rm().  As a result,
'c' is deleted
unintentionally.
> a <- 1:5
> b <- 'abc'
> c <- letters
> ls()
[1] "a" "b" "c"
> rm(c('a','b'))
> ls()
character(0)
>

Same behaviour seen on Apple Mac OSX 10.4.8 platform:
> sessionInfo()
R version 2.4.0 Patched (2006-10-31 r39758) 
powerpc-apple-darwin8.8.0 

locale:
en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8

attached base packages:
[1] "methods"   "stats"     "graphics" 
"grDevices" "utils"     "datasets" 
"base"

other attached packages:
    XML 
"1.2-0" 
> 
> ls()
[1] "getMonograph" "last.warning" "myfun"      
> a <- 1
> b <- 2
> c <- letters
> a
[1] 1
> b
[1] 2
> c
 [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p" "q" "r" "s" "t"
"u" "v" "w" "x" "y"
"z"
> rm(c('a', 'b'))
> a
Error: object "a" not found
> b
Error: object "b" not found
> c
.Primitive("c")
> ls()
[1] "getMonograph" "last.warning" "myfun"      
> a <- 1
> b <- 2
> d <- letters
> ls()
[1] "a"            "b"            "d"           
"getMonograph" "last.warning" "myfun"      
> rm(c('a', 'b'))
Warning message:
remove: variable "c" was not found 
> ls()
[1] "d"            "getMonograph" "last.warning"
"myfun"       
> 
Steven McKinney

Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre

email: smckinney at bccrc.ca

tel: 604-675-8000 x7561

BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C. 
V5Z 1L3
Canada




-----Original Message-----
From: r-devel-bounces at r-project.org on behalf of hanl2 at wyeth.com
Sent: Wed 11/29/2006 10:35 AM
To: r-devel at stat.math.ethz.ch
Cc: R-bugs at biostat.ku.dk
Subject: [Rd] rm() deletes 'c' if c('a','b') is the
argument (PR#9399)
 
Full_Name: Lixin Han
Version: 2.4.0
OS: Windows 2000
Submission from: (NULL) (155.94.110.222)


A character vector c('a','b') is supplied to rm().  As a result,
'c' is deleted
unintentionally.
> a <- 1:5
> b <- 'abc'
> c <- letters
> ls()
[1] "a" "b" "c"
> rm(c('a','b'))
> ls()
character(0)
>
______________________________________________
R-devel at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

However, the help page also states:
 
...the objects to be removed, supplied individually and/or as a
character vector
 
So maybe the help page needs to be changed.
 
Lixin Han
 
 
 
Lixin Han, PhD
Sr. Principal Biostatistician
Wyeth Research
35 Cambridgepark Drive
Cambridge, MA 02140
Phone: (617) 665-8642
Fax: (617) 665-8007
hanl2@wyeth.com 

>>> "James W. MacDonald" <jmacdon@med.umich.edu>
11/29/2006 2:14 PM
>>>
That's because you are not using rm() correctly. From the help page:

Arguments:

      ...: the objects to be removed, supplied individually and/or as
a
           character vector

     list: a character vector naming objects to be removed.

So if you pass an unnamed argument, rm() will assume you have some 
objects in the .GlobalEnv with those names that you would like to 
remove. If you want to pass a character vector, you have to name it 
because the first argument is '...'.
> a <- 1:5
> b <- 2:10
> c <- "not a good variable name"
> rm(list=c("a","b"))
> c
[1] "not a good variable name"
> a <- 1:5
> b <- 2:10
> c <- "still not a good variable name"
> rm(a,b)
> c
[1] "still not a good variable name"
> a <- 1:5
> b <- 2:10
> c <- "still not a good variable name"
> rm("a","b")
> c
[1] "still not a good variable name"


NB: 'c' is not a good variable name because you are masking an existing

function.

An argument could be made that the explanation for the first argument
is 
not very exact.

Best,

Jim



Steven McKinney wrote:
> Same behaviour seen on Apple Mac OSX 10.4.8 platform:
> 
> 
>>sessionInfo()
> 
> R version 2.4.0 Patched (2006-10-31 r39758) 
> powerpc-apple-darwin8.8.0 
> 
> locale:
> en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8
> 
> attached base packages:
> [1] "methods"   "stats"     "graphics" 
"grDevices" "utils"
"datasets"  "base"     
> 
> other attached packages:
>     XML 
> "1.2-0" 
> 
>>ls()
> 
> [1] "getMonograph" "last.warning" "myfun"
> 
>>a <- 1
>>b <- 2
>>c <- letters
>>a
> 
> [1] 1
> 
>>b
> 
> [1] 2
> 
>>c
> 
>  [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p"
"q" "r" "s" "t" "u"
"v" "w" "x" "y"
"z"
> 
>>rm(c('a', 'b'))
>>a
> 
> Error: object "a" not found
> 
>>b
> 
> Error: object "b" not found
> 
>>c
> 
> .Primitive("c")
> 
>>ls()
> 
> [1] "getMonograph" "last.warning" "myfun"
> 
>>a <- 1
>>b <- 2
>>d <- letters
>>ls()
> 
> [1] "a"            "b"            "d"        
"getMonograph"
"last.warning" "myfun"       
> 
>>rm(c('a', 'b'))
> 
> Warning message:
> remove: variable "c" was not found 
> 
>>ls()
> 
> [1] "d"            "getMonograph"
"last.warning" "myfun"
> 
> 
> Steven McKinney
> 
> Statistician
> Molecular Oncology and Breast Cancer Program
> British Columbia Cancer Research Centre
> 
> email: smckinney@bccrc.ca 
> 
> tel: 604-675-8000 x7561
> 
> BCCRC
> Molecular Oncology
> 675 West 10th Ave, Floor 4
> Vancouver B.C. 
> V5Z 1L3
> Canada
> 
> 
> 
> 
> -----Original Message-----
> From: r-devel-bounces@r-project.org on behalf of hanl2@wyeth.com 
> Sent: Wed 11/29/2006 10:35 AM
> To: r-devel@stat.math.ethz.ch 
> Cc: R-bugs@biostat.ku.dk 
> Subject: [Rd] rm() deletes 'c' if c('a','b') is the
argument
(PR#9399)
>  
> Full_Name: Lixin Han
> Version: 2.4.0
> OS: Windows 2000
> Submission from: (NULL) (155.94.110.222)
> 
> 
> A character vector c('a','b') is supplied to rm().  As a
result, 'c'
is deleted
> unintentionally.
> 
> 
>>a <- 1:5
>>b <- 'abc'
>>c <- letters
>>ls()
> 
> [1] "a" "b" "c"
> 
>>rm(c('a','b'))
>>ls()
> 
> character(0)
> 
> 
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel 
> 
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel 

-- 
James W. MacDonald, M.S.
Biostatistician
Affymetrix and cDNA Microarray Core
University of Michigan Cancer Center
1500 E. Medical Center Drive
7410 CCGC
Ann Arbor MI 48109
734-647-5623


**********************************************************
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Steven McKinney wrote:
> Same behaviour seen on Apple Mac OSX 10.4.8 platform:
>
>   
>> sessionInfo()
>>     
> R version 2.4.0 Patched (2006-10-31 r39758) 
> powerpc-apple-darwin8.8.0 
>
> locale:
> en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8
>
> attached base packages:
> [1] "methods"   "stats"     "graphics" 
"grDevices" "utils"     "datasets" 
"base"
>
> other attached packages:
>     XML 
> "1.2-0" 
>   
>> ls()
>>     
> [1] "getMonograph" "last.warning" "myfun"
>   
>> a <- 1
>> b <- 2
>> c <- letters
>> a
>>     
> [1] 1
>   
>> b
>>     
> [1] 2
>   
>> c
>>     
>  [1] "a" "b" "c" "d" "e"
"f" "g" "h" "i" "j"
"k" "l" "m" "n" "o"
"p" "q" "r" "s" "t"
"u" "v" "w" "x" "y"
"z"
>   
>> rm(c('a', 'b'))
>> a
>>     
> Error: object "a" not found
>   
>> b
>>     
> Error: object "b" not found
>   
>> c
>>     
> .Primitive("c")
>   
>> ls()
>>     
> [1] "getMonograph" "last.warning" "myfun"
>   
>> a <- 1
>> b <- 2
>> d <- letters
>> ls()
>>     
> [1] "a"            "b"            "d"        
"getMonograph" "last.warning" "myfun"
>   
>> rm(c('a', 'b'))
>>     
> Warning message:
> remove: variable "c" was not found 
>   
>> ls()
>>     
> [1] "d"            "getMonograph"
"last.warning" "myfun"
>   
>
> Steven McKinney
>
> Statistician
> Molecular Oncology and Breast Cancer Program
> British Columbia Cancer Research Centre
>
> email: smckinney at bccrc.ca
>
> tel: 604-675-8000 x7561
>
> BCCRC
> Molecular Oncology
> 675 West 10th Ave, Floor 4
> Vancouver B.C. 
> V5Z 1L3
> Canada
>
>
>
>
> -----Original Message-----
> From: r-devel-bounces at r-project.org on behalf of hanl2 at wyeth.com
> Sent: Wed 11/29/2006 10:35 AM
> To: r-devel at stat.math.ethz.ch
> Cc: R-bugs at biostat.ku.dk
> Subject: [Rd] rm() deletes 'c' if c('a','b') is the
argument (PR#9399)
>  
> Full_Name: Lixin Han
> Version: 2.4.0
> OS: Windows 2000
> Submission from: (NULL) (155.94.110.222)
>
>
> A character vector c('a','b') is supplied to rm().  As a
result, 'c' is deleted
> unintentionally.
>
>   
>> a <- 1:5
>> b <- 'abc'
>> c <- letters
>> ls()
>>     
> [1] "a" "b" "c"
>   
>> rm(c('a','b'))
>> ls()
>>     
> character(0)
>   
>
>   
The reason is that
 > x <- function(...) sapply(match.call(expand.dots = FALSE)$..., 
as.character)
 > x(c(a,b))
     [,1]
[1,] "c"
[2,] "a"
[3,] "b"

Which in turn happens because
 > as.character(quote(c(a,b)))
[1] "c" "a" "b"

I don't know if it really qualifies as a bug, but it's not documented 
that as.character() is used and I suppose we could be more careful with 
the argument checking.

On Wed, 29 Nov 2006 p.dalgaard at biostat.ku.dk wrote:
> > A character vector c('a','b') is supplied to rm().
> > As a result, 'c' is deleted unintentionally.
> > ...
> >> a <- 1:5
> >> b <- 'abc'
> >> c <- letters
> >> ls()
> > [1] "a" "b" "c"
> >> rm(c('a','b'))
> >> ls()
> > character(0)
> ...
> I don't know if it really qualifies as a bug, but it's not
documented
> that as.character() is used and I suppose we could be more careful with
> the argument checking.
I suggest that if any changes are made, then
rm(c('a','b')) should throw an error.

Functions which try to be "user-friendly" by
letting you omit quotes are generally a bad
idea, IMO.  They all need patching up in various
ways to work in all situation (e.g., library's
character.only=TRUE argument and the complicated
code in help to see what the topic really is).

Perhaps rm() should be deprecated in favor of
remove(), which uses standard S syntax rules.

----------------------------------------------------------------------------
Bill Dunlap
Insightful Corporation
bill at insightful dot com
360-428-8146

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