[R-sig-Geo] paste(" /" ") and paste(" /' ") for grass command

[Agustin Lobo]

True. Also, actually grass accepts where='(GRIDCODE = 11917)', so the 
practical problem is solved.
Nevertheless, I find odd the different behavior of

paste("\"","Hola","\"",sep="")
and
paste("\'","Hola","\'",sep="")

the former printing the \
while the second one does not.

Thanks!

Agus

Jaime R. Garcia Marquez wrote:
> Dear Agustin,
>
> I think that using the script paste("\"","Hola","\"",sep="") will do 
> the job anyway. Yes, you would get "\"Hola\"" as a result but when you 
> pass the script to GRASS the \ symbol will not be considered and so 
> you will get the string you are looking for.
>
> a <- "v.extract codigo_Montseny07_clump"
> b <- paste("out=extract", 11917, sep="")
> c <- paste("(GRIDCODE = ", 11917, ")", sep="")
> c <- paste("where=\"", c, "\"",sep="")
>
> string <- paste(a,b,c, sep=" ")
> system(string)
>
>> string
> [1] "v.extract codigo_Montseny07_clump out=extract11917 
> where=\"(GRIDCODE = 11917)\""
>
> When the command is read in GRASS the \ symbol will mean move to the 
> next line in the console.
>
> Best,
>
> Jaime -R
>
>
> On Wed, 22 Apr 2009 10:31:55 +0200, Agustin Lobo 
> <alobolistas at gmail.com> wrote:
>
>> I wish to write "" using paste(), but
>>
>>> paste("\"","Hola","\"",sep="")
>> [1] "\"Hola\""
>>>
>>
>> while the same approach works with ''
>>> paste("\'","Hola","\'",sep="")
>> [1] "'Hola'"
>>
>> why this difference? how could I do it to get "Hola" ?
>>
>> I need this to write this string in R:
>> v.extract codigo_Montseny07_clump out=extract11917 where="(GRIDCODE =
>> 11917)"
>>
>> and pass it to grass. Something like:
>> for (i in polis){
>> system("g.region vect=codigo_Montseny07_clump")
>> nomextract <- paste("extract",i,sep="")
>> grcomm <- paste("v.extract codigo_Montseny07_clump out=",nomextract,
>> " where=\"(GRIDCODE = ",i,")\" ",sep="")
>> system(grcomm)
>>
>> ...
>>
>> Thanks
>>
>> Agus
>
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