R help - Jul 2009 - concatenating multiple columns from files

R-users,
I want to concatenate columns from different files in a  single object. 
I'm doing bad. My peace of code is as follow:

rawdata <- list.files("./data")

for (i in rawdata) {
  mat[ ] <- read.table(paste(i ,sep=""))
}

At the end of the loop I have just one column. What I'm doing wrong?
Thanks,
Fred

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Here is a suggestion:

rawdata <- list.files("./data")
mat <- list()

for(i in rawdata) 
	mat[[i]] <- read.table(file.path("./data", i))

mat <- data.frame(mat)

  


Bill Venables
http://www.cmis.csiro.au/bill.venables/ 


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of ferreirafm
Sent: Friday, 31 July 2009 8:46 AM
To: r-help at r-project.org
Subject: [R] concatenating multiple columns from files


R-users,
I want to concatenate columns from different files in a  single object. 
I'm doing bad. My peace of code is as follow:

rawdata <- list.files("./data")

for (i in rawdata) {
  mat <- read.table(paste(i ,sep=""))
}

At the end of the loop I have just one column. What I'm doing wrong?
Thanks,


-- 
View this message in context:
http://www.nabble.com/concatenating-multiple-columns-from-files-tp24748542p24748542.html
Sent from the R help mailing list archive at Nabble.com.

______________________________________________
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.

You can do something like

mat <- do.call(cbind, lapply(list.files(".data"),read.table))


## explanation:

lapply(list.files(".data"),read.table)
will store all tables in a list

do.call(cbind,...)
will bind all the columns stored in the list created above.


----- Original Message ----
From: ferreirafm <ferreirafm at lim12.fm.usp.br>
To: r-help at r-project.org
Sent: Thursday, July 30, 2009 5:29:46 PM
Subject: [R]  concatenating multiple columns from files


R-users,
I want to concatenate columns from different files in a  single object. 
I'm doing bad. My peace of code is as follow:

rawdata <- list.files("./data")

for (i in rawdata) {
  mat[ ] <- read.table(paste(i ,sep=""))
}

At the end of the loop I have just one column. What I'm doing wrong?
Thanks,
Fred

-- 
View this message in context:
http://www.nabble.com/concatenating-multiple-columns-from-files-tp24748542p24748542.html
Sent from the R help mailing list archive at Nabble.com.

______________________________________________
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.