Re: [Rd] rm() deletes 'c' if c('a','b') is the argument (PR#9399)

From: James W. MacDonald <jmacdon_at_med.umich.edu>
Date: Wed 29 Nov 2006 - 19:14:40 GMT

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)
>
>
> ______________________________________________
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> 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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