extract.from.files: Extract information from files.
In haberdashPI/wright.lab.util: A set of utilitiy functions used in our lab.

TODO

1	extract.from.files(filenames, format, what)

`filenames`
`format`
`what`

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (filenames, format, what) 
{
    pattern = format$pattern
    replace = format[[what]]
    good.files = grepl(pattern, filenames)
    for (bad.file in filenames[!good.files]) {
        warning(paste("File \"", bad.file, "\" does not appear to follow the correct", 
            " filenaming convention.", sep = ""))
    }
    result = rep(NA, length(filenames))
    if (what == "day") {
        if (is.null(format$day)) {
            result[good.files] = strptime(file.info(filenaems[good.files])$mtime, 
                "%Y-%m-%d")
        }
        else {
            result[good.files] = sub(pattern, replace, filenames[good.files])
        }
    }
    else result[good.files] = sub(pattern, replace, filenames[good.files])
    result
  }