R help - May 2012 - Reading a bunch of csv files into R

Dear R users


I am struggling from a data importing issue:

I have some hundreds of csv files needed to be read into R for futher
analysis. All those csv files are named in one of the three formats:

(1) strings: e.g. London_Oxford street
(2) Integer: e.g. 1234_5678
(3) combined: e.g. London_1234

I intend to use read.csv("xxxx_xxx.csv") but I only dealt with
sigle documents before and if there are only no more than 20 files, I do
not bother to search a more efficient way.


Is there any claver way that I do not have to type in all these hundreds
names by hand, maybe using a R package or write some code in some other
languages if it is not too difficult to learn.

Any thoughts/hints please??

Many thanks in advance!

HJ

	[[alternative HTML version deleted]]

See ?dir

Assign the value to a vector and loop over the elements of the vector.

Kevin


On Fri, May 25, 2012 at 12:16 PM, HJ YAN <yhj204 at googlemail.com>
wrote:
> Dear R users
>
>
> I am struggling from a data importing issue:
>
> I have some hundreds of csv files needed to be read into R for futher
> analysis. All those csv files are named in one of the three formats:
>
> (1) strings: e.g. London_Oxford street
> (2) Integer: e.g. 1234_5678
> (3) combined: e.g. London_1234
>
> I intend to use read.csv("xxxx_xxx.csv") but I only dealt with
> sigle documents before and if there are only no more than 20 files, I do
> not bother to search a more efficient way.
>
>
> Is there any claver way that I do not have to type in all these hundreds
> names by hand, maybe using a R package or write some code in some other
> languages if it is not too difficult to learn.
>
> Any thoughts/hints please??
>
> Many thanks in advance!
>
> HJ
>
> ? ? ? ?[[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.


-- 
Kevin Wright

HJ, try something like this:

   files <- list.files(pattern = "\\.(csv|CSV)$")

    for (i in 1:length(files)) {
            temp <- read.csv(files[i], header = FALSE)
 ... do whatever you want with the contents of temp...
    }

Bryan
***********
Bryan Hanson
Professor of Chemistry & Biochemistry
DePauw University

On May 25, 2012, at 1:16 PM, HJ YAN wrote:
> Dear R users
> 
> 
> I am struggling from a data importing issue:
> 
> I have some hundreds of csv files needed to be read into R for futher
> analysis. All those csv files are named in one of the three formats:
> 
> (1) strings: e.g. London_Oxford street
> (2) Integer: e.g. 1234_5678
> (3) combined: e.g. London_1234
> 
> I intend to use read.csv("xxxx_xxx.csv") but I only dealt with
> sigle documents before and if there are only no more than 20 files, I do
> not bother to search a more efficient way.
> 
> 
> Is there any claver way that I do not have to type in all these hundreds
> names by hand, maybe using a R package or write some code in some other
> languages if it is not too difficult to learn.
> 
> Any thoughts/hints please??
> 
> Many thanks in advance!
> 
> HJ
> 
> 	[[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.

For example:

myDir <- "some file path" 
filenames <- list.files(myDir)
filenames <- filenames[grep("[.]csv", filenames)]

data_names <- gsub("[.]csv", "", filenames)

for(i in 1:length(filenames)) assign(data_names[i], read.csv(file.path(myDir,
filenames[i])))

?

 Benjamin Nutter |??Biostatistician   ? |??Quantitative Health Sciences
? Cleveland Clinic?   | ?9500 Euclid Ave.? | ?Cleveland, OH 44195? |?(216)
445-1365


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Kevin Wright
Sent: Friday, May 25, 2012 2:55 PM
To: HJ YAN
Cc: r-help at r-project.org
Subject: Re: [R] Reading a bunch of csv files into R

See ?dir

Assign the value to a vector and loop over the elements of the vector.

Kevin


On Fri, May 25, 2012 at 12:16 PM, HJ YAN <yhj204 at googlemail.com>
wrote:
> Dear R users
>
>
> I am struggling from a data importing issue:
>
> I have some hundreds of csv files needed to be read into R for futher 
> analysis. All those csv files are named in one of the three formats:
>
> (1) strings: e.g. London_Oxford street
> (2) Integer: e.g. 1234_5678
> (3) combined: e.g. London_1234
>
> I intend to use read.csv("xxxx_xxx.csv") but I only dealt with
sigle
> documents before and if there are only no more than 20 files, I do not 
> bother to search a more efficient way.
>
>
> Is there any claver way that I do not have to type in all these 
> hundreds names by hand, maybe using a R package or write some code in 
> some other languages if it is not too difficult to learn.
>
> Any thoughts/hints please??
>
> Many thanks in advance!
>
> HJ
>
> ? ? ? ?[[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.


--
Kevin Wright

______________________________________________
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.


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On Fri, 25 May 2012, HJ YAN wrote:
> Is there any claver way that I do not have to type in all these hundreds
> names by hand, maybe using a R package or write some code in some other
> languages if it is not too difficult to learn.
   I'd put the list of commands in a shell script; e.g.,

# import_files.R
read_csv("file1.csv", header = T, sep = ',')
read_csv("file2.csv", header = T, sep = ',')

etc.

   Then, within a R session, run

source("/full/path/to/import_files.R")

or, on the command line,

R CMD BATCH /full/path/name/to/import_files.R

   You'll still need to list all the files individually unless you use a
loop. I've not tried that so someone more experienced will advise you on
that.

Rich