[R] Loop Help

[David L Carlson]

I should have added

TOWER$Tower <- factor(TOWER$Tower)

To the end to convert Tower from an integer to a factor.

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of David L Carlson
> Sent: Monday, May 21, 2012 12:30 PM
> To: 'Rui Barradas'; 'bdossman'
> Cc: r-help at r-project.org
> Subject: Re: [R] Loop Help
> 
> Here is a slightly different approach that takes advantage of
> recycling:
> 
> # Make 7 data frames
> for (i in 1:7) {
>   assign(paste("TOWER", i, sep=""), data.frame(A=letters[1:4],
>     X=rnorm(4)))
> }
> # Add Tower column taking advantage of recyling
> tnames <- paste("TOWER", 1:7, sep="")
> for (i in 1:7) {
>   assign(tnames[i], cbind(eval(as.name(tnames[i])), Tower=i))
> }
> # Combine them into a single data frame
> TOWER <- do.call(rbind, lapply(tnames, as.name))
> 
> 
> > -----Original Message-----
> > From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> > project.org] On Behalf Of Rui Barradas
> > Sent: Saturday, May 19, 2012 9:04 AM
> > To: bdossman
> > Cc: r-help at r-project.org
> > Subject: Re: [R] Loop Help
> >
> > Hello,
> >
> > The error is that you are trying to use the number of rows of a
> > character string.
> > TOWERS[1], TOWERS[2], etc, are not data frames. Use a print statement
> > before the line that throws the error to check it.
> >
> > Your problem can be solved along the lines of what follows.
> > Note that I've put all data frames in a list, it's better to have
> them
> > kept like that, it makes everything else simpler.
> >
> >
> > # Create a list with some made up data.frames
> > towers <- list(TOWER1=data.frame(A=letters[1:4], X=rnorm(4)),
> >      TOWER2=data.frame(A=LETTERS[1:6], X=runif(6)))
> > towers
> >
> > # In your case this is  from TOWER1 to TOWER7
> > TOWERS <- names(towers)
> >
> > towers.with.id <- lapply(TOWERS, function(i){
> >          towers[[ i ]]$Tower <- factor(i)
> >          towers[[ i ]]})
> >
> >
> > (Use something other than 'towers.with.id', this is just an example.)
> >
> >
> > #names(towers.with.id) <- TOWERS  # (*) See below
> > towers.with.id
> > do.call(rbind, towers.with.id)
> >
> >
> > (*) Try to run these last three instructions with the marked line
> > commented/uncommented.
> > It's better to uncomment, maybe after rbind.
> > You'll later be able to access the list elements with a syntax like
> >
> >
> > towers.with.id[[ "TOWER2" ]]        # full data.frame 2
> > towers.with.id[[ TOWERS[2] ]]$A    # just that column
> > towers.with.id[[ "TOWER2" ]]$A[3]    # third element of that column
> >
> >
> > If you do.call/rbind before, to solve the rbind-ed data.frame's row
> > names use
> >
> > rownames(result) <- seq.int(nrow(result))
> >
> > where 'result' is the result of do.call.
> >
> > Hope this helps,
> >
> > Rui Barradas
> >
> > Em 19-05-2012 11:00, r-help-request at r-project.org escreveu:
> > > Date: Fri, 18 May 2012 16:14:08 -0700 (PDT)
> > > From: bdossman<bdossman at gmail.com>
> > > To:r-help at r-project.org
> > > Subject: [R] Loop Help
> > > Message-ID:<1337382848213-4630555.post at n4.nabble.com>
> > > Content-Type: text/plain; charset=us-ascii
> > >
> > > Hi all,
> > >
> > > I am a beginner R user and need some help with a simple loop
> > function.
> > >
> > > Currently, I have seven datasets (TOWER1,TOWER2...TOWER7) that are
> > all in
> > > the same format (same # of col and headers). I am trying to add a
> new
> > column
> > > (factor) to each dataset that simply identifies the dataset.
> > Ultimately, I
> > > would like to merge all 7 datasets and need that column to identify
> > what
> > > rows came from what dataset.
> > >
> > > Using the code below, I get the error message "Error in rep(i,
> > > nrow(TOWER.i)) : invalid 'times' argument" but it doesn't make
> sense
> > to me
> > > since nrow should give an integer value. Any help will be really
> > > appreciated.
> > >
> > > TOWERS<-
> > c("TOWER1","TOWER2","TOWER3","TOWER4","TOWER5","TOWER6","TOWER7")
> > >
> > > for(i in 1:7){
> > > 	TOWER.i<-TOWERS[i]
> > > 	TOWER<-rep(i,nrow(TOWER.i))
> > > 	TOWER.i<-cbind(TOWER.i[1:2],TOWER, TOWER.i[2:length(TOWER.i)])
> > > }
> >
> > ______________________________________________
> > 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.
> 
> ______________________________________________
> 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.