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I have a 100 text files with matrices which I want to open using R - the read.table() command can be used for that. I cant figure out how to assign these files to separate variable names so that I can carry out operations on the matrices. I am trying to use the for loop but keep getting error messages. I hope somebody can help me out with this...

user2203793
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  • incidentally, the answer here might be helpful http://stackoverflow.com/questions/15593001/how-to-upload-a-folder-consisting-of-folders-in-r-for-windows-i-am-uploading-v/15593645#15593645 – Ricardo Saporta Mar 24 '13 at 04:09

2 Answers2

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If you have 100 files, it may make more sense to simply keep them in one neat list. 

  # Get the list of files
  #----------------------------#
    folder <- "path/to/files"
    fileList <- dir(folder, recursive=TRUE)  # grep through these, if you are not loading them all

    # use platform appropriate separator
    files <- paste(folder, fileList, sep=.Platform$file.sep)


  # Read them in
  #----------------------------#
    myMatrices <- lapply(files, read.table)

Then access via, eg, myMatrices[[37]] or using lapply

Ricardo Saporta
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  • @user2203793, you need to use double-brackets. Take a look at the difference between `myMatricies[1]` and `myMatricies[[1]]`. The latter is a matrix and the former is a list containing only one element, that element is a matrix. `+` does not make sense for lists, but it does for matrices. – Ricardo Saporta Mar 24 '13 at 05:13
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Would it be easer to just use list.files?

For example: 

files <- list.files(directory/path, pattern= "regexp.if.needed")

And then you could access each element by calling files[1], files[2], etc. This would allow you to pull out either all the files in a directory, or just the ones that matched a regular expression.

SummerEla
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