compression - Automate zip file reading in R

Question

I need to automate R to read a csv datafile that's into a zip file.

For example, I would type:

read.zip(file = "myfile.zip")

And internally, what would be done is:

• Unzip myfile.zip to a temporary folder
• Read the only file contained on it using read.csv

If there is more than one file into the zip file, an error is thrown.

My problem is to get the name of the file contained into the zip file, in orded to provide it do the read.csv command. Does anyone know how to do it?

UPDATE

Here's the function I wrote based on @Paul answer:

read.zip <- function(zipfile, row.names=NULL, dec=".") {
    # Create a name for the dir where we'll unzip
    zipdir <- tempfile()
    # Create the dir using that name
    dir.create(zipdir)
    # Unzip the file into the dir
    unzip(zipfile, exdir=zipdir)
    # Get the files into the dir
    files <- list.files(zipdir)
    # Throw an error if there's more than one
    if(length(files)>1) stop("More than one data file inside zip")
    # Get the full name of the file
    file <- paste(zipdir, files[1], sep="/")
    # Read the file
    read.csv(file, row.names, dec)
}

Since I'll be working with more files inside the tempdir(), I created a new dir inside it, so I don't get confused with the files. I hope it may be useful!

Answer 1

Another solution using unz:

read.zip <- function(file, ...) {
  zipFileInfo <- unzip(file, list=TRUE)
  if(nrow(zipFileInfo) > 1)
    stop("More than one data file inside zip")
  else
    read.csv(unz(file, as.character(zipFileInfo$Name)), ...)
}