[R-sig-Geo] as() and conversion from character to factor

[MacQueen, Don]

Thank you.

-Don

-- 
Don MacQueen

Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062





On 10/7/12 8:26 AM, "Edzer Pebesma" <edzer.pebesma at uni-muenster.de> wrote:

>For now, you should be able to prevent this by starting your script with
>an
>
>options(stringsAsFactors = FALSE)
>
>but in future releases, sp will not do this conversion.
>
>Thanks,
>
>On 10/04/2012 09:31 PM, MacQueen, Don wrote:
>> I just noticed that in the following sequence the final step to
>> SpatialGridDataFrame converts the character column to factor, whereas
>>the
>> previous ones do not. Source the following little script, and it will
>> hopefully show what I'm seeing. Shouldn't this be consistent?
>> 
>> Thanks
>> -Don
>> 
>> 
>> require(sp)
>> require(maptools)
>> 
>> tstdf <- expand.grid(x=1:3, y=1:3)
>> tstdf$ch <- rep('a',nrow(tstdf))
>> 
>> tstsp <- tstdf
>> coordinates(tstsp) <- c('x','y')
>> proj4string(tstsp) <- CRS('+init=epsg:32610')
>> 
>> tstpx <- as(tstsp, "SpatialPixelsDataFrame")
>> 
>> tstgrd <- as(tstpx, "SpatialGridDataFrame")
>> 
>> print(class(tstdf$ch))
>> print(class(tstsp$ch))
>> print(class(tstpx$ch))
>> print(class(tstgrd$ch))
>> 
>> 
>> #########
>> I get:
>> 
>>> print(class(tstdf$ch))
>> [1] "character"
>>> print(class(tstsp$ch))
>> [1] "character"
>>> print(class(tstpx$ch))
>> [1] "character"
>>> print(class(tstgrd$ch))
>> [1] "factor"
>> #########
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>>> sessionInfo()
>> R version 2.15.1 (2012-06-22)
>> Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
>> 
>> locale:
>> [1] C
>> 
>> attached base packages:
>> [1] stats     utils     datasets  grDevices graphics  methods   base
>> 
>> other attached packages:
>> [1] maptools_0.8-16 lattice_0.20-6  foreign_0.8-50  sp_1.0-0
>> 
>> loaded via a namespace (and not attached):
>> [1] grid_2.15.1 rmacq_1.1-8
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>> 
>
>-- 
>Edzer Pebesma
>Institute for Geoinformatics (ifgi), University of Münster
>Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
>8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
>http://www.52north.org/geostatistics      e.pebesma at wwu.de
>
>_______________________________________________
>R-sig-Geo mailing list
>R-sig-Geo at r-project.org
>https://stat.ethz.ch/mailman/listinfo/r-sig-geo