[R] For loop output

[MacQueen, Don]

If I understand the request correctly, here is an easy to follow example:
(I'm using the first four letters as surrogates for the file names)
(and assuming we want quotes at both the beginning and the end)


> tmp <- letters[1:4]
> tmp
[1] "a" "b" "c" "d"

> foo <- paste( "'", paste(tmp,collapse="','"), "'", sep='')
> cat(foo,'\n')
'a','b','c','d' 

In this case, cat() does a better job than print() of telling you exactly
what you have.
I use this sort of thing to construct arguments for the SQL "in" clause)



-- 
Don MacQueen

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





On 8/8/13 8:05 AM, "Jenny Williams" <jenny.williams at kew.org> wrote:

>I am having difficulty storing the output of a for loop I have generated.
>All I want to do is find all the files that I have, create a string with
>all of the names in quotes and separated by commas. This is proving more
>difficult than I initially anticipated.
>I am sure it is either very simple or the construction of the for loop is
>not quite right
>The result gets automatically printed after the loop but I can't seem to
>save it.
>I have tried to create the element in advance but the result is the same:
>NULL
>
>individual.proj = 
>Sys.glob("Arabica/proj_current/individual_projections/*.img", dirmark =
>FALSE)
>individual.proj
>[1] 
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_Full_GBM.img"
> [2] 
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_Full_GLM.img"
> [3] 
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_Full_MARS.img"
> [4] 
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_Full_RF.img"
> [5] 
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_RUN10_GBM.img"
>
>
>##generate loop to create string out of the table of projected files.
>L.ip = length(individual.proj)
>  for (i in 1:L.ip){
>           individual.proj.i <- individual.proj[i]
>           individual.proj.quote = cat(paste('"', individual.proj.i, '"',
>',',sep=""))
>           }
>"Arabica/proj_current/individual_projections/proj_current_arabica_pa.data.
>tmp$pa.tab_Full_GBM.img","Arabica/proj_current/individual_projections/proj
>_current....
>
>##print output string
>individual.proj.quote
>NULL
>
>#command to be applied to individual.proj.quote to removed the final
>comma from the string
>substr(individual.proj.quote, 1, nchar(individual.proj.quote)-1)
>
>Any help or pointers would be greatly appreciated, no amount of extensive
>google searches have been fruitful so far.
>
>
>******************
>Jenny Williams
>Spatial Information Scientist, GIS Unit
>Herbarium, Library, Art & Archives Directorate
>Royal Botanic Gardens, Kew
>Richmond, TW9 3AB, UK
>
>Tel: +44 (0)208 332 5277
>email: jenny.williams at kew.org<mailto:jenny.williams at kew.org>
>******************
>
>Film: The Forgotten Home of Coffee - Beyond the
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>Stories: Coffee Expedition -
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>             Kew in Harapan Rainforest
>Sumatra<http://storify.com/KewGIS/kew-in-harapan-rainforest>
>Articles: Seeing the wood for the
>trees<http://www.kew.org/ucm/groups/public/documents/document/kppcont_0606
>02.pdf>
>How Kew's GIS team and South East Asia botanists are working to help
>conserve and restore a rainforest in Sumatra. Download a pdf of this
>article 
>here.<http://www.kew.org/ucm/groups/public/documents/document/kppcont_0606
>02.pdf>
>
>
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