[R] For loop output

Jan Kim jttkim at googlemail.com
Thu Aug 8 19:57:04 CEST 2013


On Thu, Aug 08, 2013 at 11:38:33AM -0500, Charles Determan Jr wrote:
> Hi Jenny,
> 
> Firstly, to my knowledge you cannot assign the output of cat to an object
> (i.e. it only prints it).
> Second, you can just add the 'collapse' option of the paste function.
> 
> individual.proj.quote <- paste(individual.proj, collapse = ",")
> 
> if you really want the quotes
> individual.proj.quote <- paste(individual.proj, collapse='","')

No -- the backslashes are part of the visualisation of the value, not
part of the value itself.

Please see FAQ 7.37 for details.

And also notice that the collapse parameter specifies a separator,
and the quotes are intended to enclose the individual words here,
not to separate them. In this case, the left quote of the first word
and the right quote of the last word will not be generated as a result
of this misuse of a separator...

Best regards, Jan

> but you will be stuck with some backslashes I can't recall the syntax to
> remove.
> 
> Hope this serves your purposes
> Cheers,
> 
> Charles
> 
> 
> On Thu, Aug 8, 2013 at 10:05 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>
> > ******************
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> > >
> >
> >
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> 
> 
> 
> -- 
> Charles Determan
> Integrated Biosciences PhD Candidate
> University of Minnesota
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

-- 
 +- Jan T. Kim -------------------------------------------------------+
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