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Jannetta Steyn

2013-Jul-11 13:01 UTC

[R] Reading a list of filenames from a csv file

What would be the best way to read a list of filenames and headings from a
csv file?

The CSV file is structured as two columns, with column one being the
filename and column two being a heading e.g.:
ANA110915004A_3PERIOD_TmAvg-rdata.csv,Pre-DA
ANA110915006A_3PERIOD_TmAvg-rdata.csv,DA-10^-6
ANA110915012A_3PERIOD_TmAvg-rdata.csv,DA-10^-4
ANA110915016A_3PERIOD_TmAvg-rdata.csv,Washout


I want to be able to open the file using read.csv and use the heading as
the header of a graph.

Reading the filenames from the directory with list.files() works but then I
don't have the headings that go with the file e.g.:
filenames<-list.files(pattern="*.csv")
for (i in seq_along(filenames)) {
  con<-read.csv(filenames[i], headers=TRUE, sep=',')
}

I tried the code below (which I posted in a different thread) but the
solutions that people offered me didn't get it to work. The code results in
 'Error in read.table(file = file, header = header, sep = sep, quote quote, 
:
  'file' must be a character string or connection

# Read filenames from csv file
files <- read.csv(file="files.csv",head=FALSE,sep=",")

# for each filename read the file
for (i in 1:length(files)) {
  # f becomes the next row inthe file
  f<-files[i,]
  # the header to be used for the graph is in column 2 of f
  head=f[2]
  par(mfrow=c(4,2))
  # the filename to be used is in column 1 of f
  con<-read.csv(file=f[1], header=TRUE, sep=',')
  tmp<-con$value2
  data<-normalize_js(tmp,-1,1)
  time<-con$time
  # run the waveform analyser
  waveformanalyser(data,time,head)
}

Regards
Jannetta

-- 

==================================Web site: http://www.jannetta.com
Email: jannetta@henning.org
==================================
	[[alternative HTML version deleted]]

Sarah Goslee

2013-Jul-11 13:49 UTC

head link

[R] Reading a list of filenames from a csv file

Hi Janetta,

At a first guess, you need:

 files <- read.csv(file="files.csv",head=FALSE,sep=",",
stringsAsFactors=FALSE)

str(files)

would clear up any confusion as to whether the contents of the first
column of files are character or not.

If that doesn't help, then setting i <- 1 and running each line of
code in the loop individually (copy and paste) will give you a clearer
idea of where problems arise.

Sarah

On Thu, Jul 11, 2013 at 9:01 AM, Jannetta Steyn <jannetta at henning.org>
wrote:> What would be the best way to read a list of filenames and headings from a
> csv file?
>
> The CSV file is structured as two columns, with column one being the
> filename and column two being a heading e.g.:
> ANA110915004A_3PERIOD_TmAvg-rdata.csv,Pre-DA
> ANA110915006A_3PERIOD_TmAvg-rdata.csv,DA-10^-6
> ANA110915012A_3PERIOD_TmAvg-rdata.csv,DA-10^-4
> ANA110915016A_3PERIOD_TmAvg-rdata.csv,Washout
>
>
> I want to be able to open the file using read.csv and use the heading as
> the header of a graph.
>
> Reading the filenames from the directory with list.files() works but then I
> don't have the headings that go with the file e.g.:
> filenames<-list.files(pattern="*.csv")
> for (i in seq_along(filenames)) {
>   con<-read.csv(filenames[i], headers=TRUE, sep=',')
> }
>
> I tried the code below (which I posted in a different thread) but the
> solutions that people offered me didn't get it to work. The code
results in
>  'Error in read.table(file = file, header = header, sep = sep, quote
> quote,  :
>   'file' must be a character string or connection
>
> # Read filenames from csv file
> files <-
read.csv(file="files.csv",head=FALSE,sep=",")
>
> # for each filename read the file
> for (i in 1:length(files)) {
>   # f becomes the next row inthe file
>   f<-files[i,]
>   # the header to be used for the graph is in column 2 of f
>   head=f[2]
>   par(mfrow=c(4,2))
>   # the filename to be used is in column 1 of f
>   con<-read.csv(file=f[1], header=TRUE, sep=',')
>   tmp<-con$value2
>   data<-normalize_js(tmp,-1,1)
>   time<-con$time
>   # run the waveform analyser
>   waveformanalyser(data,time,head)
> }
>
> Regards
> Jannetta
>
> --
>
> ==================================> Web site: http://www.jannetta.com
> Email: jannetta at henning.org
> ==================================>
>         [[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.


-- 
Sarah Goslee
http://www.functionaldiversity.org

arun

2013-Jul-11 14:56 UTC

head link

[R] Reading a list of filenames from a csv file

Hi,
Try this:
files1<-read.csv("files.csv",header=TRUE,stringsAsFactors=FALSE)
?str(files1)
#'data.frame':??? 2 obs. of? 2 variables:
# $ Col1: chr? "ANA110915004A_3PERIOD_TmAvg-rdata.csv"
"ANA110915006A_3PERIOD_TmAvg-rdata.csv"
# $ Col2: chr? "Pre-DA" "DA-10^-6"
files1
#?????????????????????????????????? Col1???? Col2
#1 ANA110915004A_3PERIOD_TmAvg-rdata.csv?? Pre-DA
#2 ANA110915006A_3PERIOD_TmAvg-rdata.csv DA-10^-6

#Using some fake data

lapply(seq_len(nrow(files1)),function(i)
{x1<-read.csv(file=files1[i,1],header=TRUE,sep="",check.names=FALSE);x1[files1[i,2]]})
[[1]]
#? Pre-DA
#1????? 2
#2????? 3
#3????? 6
#4????? 4

#[[2]]
?# DA-10^-6
#1??????? 9
#2?????? 14
#3?????? 13
#4?????? 21


Hope this helps.
A.K.



----- Original Message -----
From: Jannetta Steyn <jannetta at henning.org>
To: r-help <r-help at r-project.org>
Cc: 
Sent: Thursday, July 11, 2013 9:01 AM
Subject: [R] Reading a list of filenames from a csv file

What would be the best way to read a list of filenames and headings from a
csv file?

The CSV file is structured as two columns, with column one being the
filename and column two being a heading e.g.:
ANA110915004A_3PERIOD_TmAvg-rdata.csv,Pre-DA
ANA110915006A_3PERIOD_TmAvg-rdata.csv,DA-10^-6
ANA110915012A_3PERIOD_TmAvg-rdata.csv,DA-10^-4
ANA110915016A_3PERIOD_TmAvg-rdata.csv,Washout


I want to be able to open the file using read.csv and use the heading as
the header of a graph.

Reading the filenames from the directory with list.files() works but then I
don't have the headings that go with the file e.g.:
filenames<-list.files(pattern="*.csv")
for (i in seq_along(filenames)) {
? con<-read.csv(filenames[i], headers=TRUE, sep=',')
}

I tried the code below (which I posted in a different thread) but the
solutions that people offered me didn't get it to work. The code results in
'Error in read.table(file = file, header = header, sep = sep, quote quote,?
:
? 'file' must be a character string or connection

# Read filenames from csv file
files <- read.csv(file="files.csv",head=FALSE,sep=",")

# for each filename read the file
for (i in 1:length(files)) {
? # f becomes the next row inthe file
? f<-files[i,]
? # the header to be used for the graph is in column 2 of f
? head=f[2]
? par(mfrow=c(4,2))
? # the filename to be used is in column 1 of f
? con<-read.csv(file=f[1], header=TRUE, sep=',')
? tmp<-con$value2
? data<-normalize_js(tmp,-1,1)
? time<-con$time
? # run the waveform analyser
? waveformanalyser(data,time,head)
}

Regards
Jannetta

-- 

==================================Web site: http://www.jannetta.com
Email: jannetta at henning.org
==================================
??? [[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.

R help - Jul 2013 - Reading a list of filenames from a csv file

[R] Reading a list of filenames from a csv file

[R] Reading a list of filenames from a csv file

[R] Reading a list of filenames from a csv file