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

[arun]

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

-- 

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