R help - Nov 2008 - attr.all.equal() and all.equal(attributes(), attributes())

Dear All!

If I try to compare the attributes of two 
objects, I find a surprising behaviour of 
attr.all.equal(). With identical attributes I 
receive the answert NULL. If the attributes 
differ, the answer is as expecxted and differences are shown.
all.equal(attributes(), attributes()) instead 
returns TRUE, if attributes are equal.

See example:

v <- 1:5
attr(v, 'testattribute') <- 'testattribute v'
v_c <- v
attributes(v)
$testattribute
[1] "testattribute v"

attributes(v_c)
$testattribute
[1] "testattribute v"

all.equal(v, v_c)
[1] TRUE
attr.all.equal(v, v_c)
NULL  << - - - - - - - - - - here is, what I don't expected
all.equal(attributes(v), attributes(v_c))
[1] TRUE

attr(v_c, 'testattribute') <- 'testattribute v_c'
attr.all.equal(v, v_c)
[1] "Attributes: < Component 1: 1 string mismatch >"
all.equal(attributes(v), attributes(v_c))
[1] "Component 1: 1 string mismatch"

Thanks for your attention

Heinz T?chler

Version:
  platform = i386-pc-mingw32
  arch = i386
  os = mingw32
  system = i386, mingw32
  status = Patched
  major = 2
  minor = 8.0
  year = 2008
  month = 11
  day = 04
  svn rev = 46830
  language = R
  version.string = R version 2.8.0 Patched (2008-11-04 r46830)

Windows XP (build 2600) Service Pack 2

Locale:
LC_COLLATE=German_Austria.1252;LC_CTYPE=German_Austria.1252;LC_MONETARY=German_Austria.1252;LC_NUMERIC=C;LC_TIME=German_Austria.1252

Search Path:
  .GlobalEnv, package:stats, package:graphics, 
package:grDevices, package:utils, 
package:datasets, package:methods, Autoloads, package:base

Heinz Tuechler wrote:
> Dear All!
> 
> If I try to compare the attributes of two objects, I find a surprising 
> behaviour of attr.all.equal(). With identical attributes I receive the 
> answert NULL. If the attributes differ, the answer is as expecxted and 
> differences are shown.
> all.equal(attributes(), attributes()) instead returns TRUE, if 
> attributes are equal.
> 
That _is_ as documented,  although if you want to quibble, it should 
probably also have been mentioned in the Value section.

I don't know if there's a a rationale for it. The actual code goes

msg <- NULL
if (....) msg <- c(msg, some text)
if (.....
msg

so it returns NULL if none of the ifs are taken, but it could easily be 
changed to return

if (is.null(msg)) TRUE else msg

("easily" depending, of course, on how much code actually depends on
the
current behaviour...)
> See example:
> 
> v <- 1:5
> attr(v, 'testattribute') <- 'testattribute v'
> v_c <- v
> attributes(v)
> $testattribute
> [1] "testattribute v"
> 
> attributes(v_c)
> $testattribute
> [1] "testattribute v"
> 
> all.equal(v, v_c)
> [1] TRUE
> attr.all.equal(v, v_c)
> NULL  << - - - - - - - - - - here is, what I don't expected
> all.equal(attributes(v), attributes(v_c))
> [1] TRUE
> 
> attr(v_c, 'testattribute') <- 'testattribute v_c'
> attr.all.equal(v, v_c)
> [1] "Attributes: < Component 1: 1 string mismatch >"
> all.equal(attributes(v), attributes(v_c))
> [1] "Component 1: 1 string mismatch"
> 
> Thanks for your attention
> 
> Heinz T?chler
> 
> Version:
>  platform = i386-pc-mingw32
>  arch = i386
>  os = mingw32
>  system = i386, mingw32
>  status = Patched
>  major = 2
>  minor = 8.0
>  year = 2008
>  month = 11
>  day = 04
>  svn rev = 46830
>  language = R
>  version.string = R version 2.8.0 Patched (2008-11-04 r46830)
> 
> Windows XP (build 2600) Service Pack 2
> 
> Locale:
>
LC_COLLATE=German_Austria.1252;LC_CTYPE=German_Austria.1252;LC_MONETARY=German_Austria.1252;LC_NUMERIC=C;LC_TIME=German_Austria.1252
> 
> 
> Search Path:
>  .GlobalEnv, package:stats, package:graphics, package:grDevices, 
> package:utils, package:datasets, package:methods, Autoloads, package:base
> 
> ______________________________________________
> 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.

-- 
    O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
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