Thank you very much.
Actually I have to delete the quotation mark of the file name in the  file
"B_M2Q.csv"
A_FX_M.csv
and then it would work.

A similar problem emerges but I can't find a solution. The next step is to
read the date.
My date in the csv file is in the format "1981-01"
I can't read it by

as.yearmon(m2q[1,3])

How can I modify the program?

2012/7/26 Bert Gunter <gunter.berton@gene.com>

> Sorry, got cut off...
>
> On Thu, Jul 26, 2012 at 8:07 AM, Bert Gunter <bgunter@gene.com> wrote:
> > 1. m2q already is a data frame, so the m2qldf statement that follows
> > is completely unnecessary.
> >
> > 2. Please read ?read.table carefully, and especially the bit about the
> > stringsAsFactors argument. The problem is that by default character
> > strings are read in as factors, not characters strings. So you can
> > either change the way they are read in thru stringsAsFactors=FALSE or
> > otherwise as explained therein -- or convert them with as.character()
> > when you access them, e.g.
>
>  x1<-read.csv(file=as.character(m2q[1,2]))
>
> -- Bert
>
> >
> > On Thu, Jul 26, 2012 at 7:53 AM, jpm miao <miaojpm@gmail.com> wrote:
> >> Dear All,
> >>
> >>
> >>
> >>   I would like to read the data file via read.csv (the 3rd line of the
> >> following program) and the file name is stored in a dataframe. Since I
> have
> >> several files to read, I store the file names as well as the sample
> period
> >> inside a file “B_M2Q.csv” and I read the file name first, and then read
> the
> >> data file.
> >>
> >>
> >>
> >>   The content of the file "B_M2Q.csv" is
> >>
> >>   FX
> >>
> >> "A_FX_M.csv"
> >>
> >> "1981-01"
> >>
> >> "2012-06"
> >>
> >> Int
> >>
> >> "A_Int.csv"
> >>
> >> "1970-01"
> >>
> >> "2012-03"
> >>
> >>   (The file is attached to this email)
> >>
> >>
> >>   The three-line program is as follows:
> >>
> >>
> >> m2q<-read.csv(file="B_M2Q.csv", header=FALSE)  # Read the file
> containing
> >> file names and sampling periods of numerical data
> >>
> >> m2qdf<-as.data.frame(m2q)   #Make the file of filenames a dataframe
> >>   # Read the numerical data
> >>
> >> Nevertheless, there is an error when I  attempt to read the numerical
> data
> >>
> >>
> >>
> >>> x1<-read.csv(file=m2qdf[1,2])
> >>
> >> Error in read.table(file = file, header = header, sep = sep, quote =
> quote,
> >> :
> >>
> >>   'file' must be a character string or connection
> >>
> >> It is a problem of the file name , since I can read the data smoothly
> if I
> >> change the line to
> >>
> >>> x1<-read.csv(file="A_FX_M.csv")
> >>
> >> Could someone tell me what the problem is?
> >> How can modify the orignal program so that I can store the sampling
> periods
> >> and filenames in a dataframe, and then I read it?
> >> How can I correctly access a string element of a dataframe?
> >>
> >> Thanks,
> >>
> >> Miao
> >>
> >> ______________________________________________
> >> R-help@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.
> >>
> >
> >
> >
> > --
> >
> > Bert Gunter
> > Genentech Nonclinical Biostatistics
> >
> > Internal Contact Info:
> > Phone: 467-7374
> > Website:
> >
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
>
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>

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