[R-sig-Geo] help pages for CRS duplicated?

[Don MacQueen]

This does help, thank you.

-Don

At 11:16 PM +0100 3/25/09, Roger Bivand wrote:
>On Wed, 25 Mar 2009, Don MacQueen wrote:
>
>>I encountered the following. My quick and simple search of past 
>>emails in R-sig-geo didn't find any previous discussion.
>>
>>>  search()
>>".GlobalEnv"        "package:rmacq"     "package:rgdal"
>>  "package:maptools"  "package:sp"
>>  "package:foreign"   "package:stats"     "package:graphics"
>>"package:grDevices" "package:utils"     "package:datasets"
>>  "package:methods"   "Autoloads"         "package:base"
>>>
>>>  find('CRS')
>>[1] "package:sp"
>>>
>>>  ?CRS
>>Help on topic 'CRS' was found in the following packages:
>>
>>  Package               Library
>>  rgdal                 /Library/Frameworks/R.framework/Resources/library
>>  sp                    /Library/Frameworks/R.framework/Resources/library
>>
>>
>>
>>Followed by a request to identify which one to view.
>
>Since the behaviour of the class differs depending on whether rgdal 
>is available or not, it is described (somewhat differently) in both. 
>As it is, sp does not depend on rgdal but rgdal depends on sp, and 
>this is likely to continue to be the case. Note that the specific 
>versions can be accessed by:
>
>help(CRS, package=sp)
>help(CRS, package=rgdal)
>
>Further, the sp version uses examples depending on rgdal through 
>require(), but sp does not "Suggest:" rgdal to avoid circularity.
>
>The difference, as the help pages explain, is that in just sp, there 
>is no external check of the correctness of the string inserted into 
>class instances, while when rgdal is loaded, the strings are checked 
>using the PROJ.4 library.
>
>Hope this helps,
>
>Roger
>
>>
>>Thanks
>>-Don
>>
>>
>>(In case anyone wonders, rmacq is a local personal package.)
>>
>>>  sessionInfo()
>>R version 2.8.1 (2008-12-22)
>>i386-apple-darwin8.11.1
>>
>>locale:
>>C
>>
>>attached base packages:
>>[1] stats     graphics  grDevices utils     datasets  methods   base
>>
>>other attached packages:
>>[1] rmacq_1.0-2     rgdal_0.5-30    maptools_0.7-16 sp_0.9-28 foreign_0.8-30
>>
>>loaded via a namespace (and not attached):
>>[1] grid_2.8.1      lattice_0.17-17 tcltk_2.8.1     tools_2.8.1
>>Warning message:
>>'DESCRIPTION' file has 'Encoding' field and re-encoding is not possible
>>
>
>--
>Roger Bivand
>Economic Geography Section, Department of Economics, Norwegian School of
>Economics and Business Administration, Helleveien 30, N-5045 Bergen,
>Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
>e-mail: Roger.Bivand at nhh.no


-- 
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062