[R-sig-Geo] Converting Grid to factor list

[Edzer J. Pebesma]

Ronnie Babigumira wrote:

>Edzer
>Many thanks. The grid was created in ArcView and exported as an ascii file. I then read it in R using the read.asciigrid 
>function in map tools
>
>Any ideas?
>  
>
Yes; the function returns an object of class SpatialGridDataFrame:

 > example(read.asciigrid)

rd.scg> x <- read.asciigrid(system.file("external/test.ag",
    package = "sp")[1])

rd.scg> class(x)
[1] "SpatialGridDataFrame"
attr(,"package")
[1] "sp"

rd.scg> image(x)
 > names(x)
[1] "/home/edzer/S/library/sp/external/test.ag"
 > names(x) = "foo"
 > f = factor(round(x$foo))
 > summary(f)
    357     394     270     310     398     294     295     303     
307     391
     18      18      17      17      17      16      16      16      
16      16
 [etc., etc.,...]
    250     256     265     274     290     291     297     299 
(Other)    NA's
      9       9       9       9       9       9       9       9    
1938    6097
 >

The renaming to foo was not necessary, but quotes would have
been necessary around the name as it contained slashes. I rounded
the values because they were numeric.
--
Edzer

>Ronnie
>
>Edzer J. Pebesma wrote:
>  
>
>>Ronnie, you didn't tell us how you created the grid. Is it on of the
>>grid classes in package sp? In that case you can address the
>>variable in it by it's name, say foo:
>>
>>mygrid.f <- factor(mygrid$foo)
>>
>>hth,
>>-- 
>>Edzer
>>
>>Ronnie Babigumira wrote:
>>
>>    
>>
>>>Hi listers
>>>I would like to change a grid to a factor list so as to apply Join 
>>>Count statistics however when I use
>>>mygrid.f <- factor(mygrid)
>>>
>>>I get an error message " 'x' must be atomic".
>>>
>>>Looking through the RHelp archives, I have chanced on emails with a 
>>>similar problem but no direct answer to this. Is anyone farmiliar with 
>>>this and how can I go about it
>>>
>>>
>>>Many thanks
>>>
>>>Ronnie
>>>
>>>_______________________________________________
>>>R-sig-Geo mailing list
>>>R-sig-Geo at stat.math.ethz.ch
>>>https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>> 
>>>
>>>      
>>>
>>    
>>
>
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