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I wish to get the fully qualified name of a file in R, given any of the standard notations. For example:
path.expand)By fully qualified file name I mean, for example, (on a Unix-like system):
/home/user/some/path/file.ext
(Edited - use file.path and attempt Windows support) A crude implementation might be:
path.qualify <- function(path) {
path <- path.expand(path)
if(!grepl("^/|([A-Z|a-z]:)", path)) path <- file.path(getwd(),path)
path
}
However, I'd ideally like something cross-platform that can handle relative paths with ../, symlinks etc. An R-only solution would be preferred (rather than shell scripting or similar), but I can't find any straightforward way of doing this, short of coding it "from scratch".
Any ideas?
503
The term fully qualified file name (or FQFN) means a file on a computer whose exact name is completely specified such that it is unambiguous and cannot be mistaken for any other file on that computer system.
To list all files in a directory in R programming language we use list. files(). This function produces a list containing the names of files in the named directory. It returns a character vector containing the names of the files in the specified directories.
If we want to check the current directory of the R script, we can use getwd( ) function. For getwd( ), no need to pass any parameters. If we run this function we will get the current working directory or current path of the R script. To change the current working directory we need to use a function called setwd( ).
In R, the function file. path() is used to fill in the directory separator.
I think you want normalizePath():
> setwd("~/tmp/bar")
> normalizePath("../tmp.R")
[1] "/home/gavin/tmp/tmp.R"
> normalizePath("~/tmp/tmp.R")
[1] "/home/gavin/tmp/tmp.R"
> normalizePath("./foo.R")
[1] "/home/gavin/tmp/bar/foo.R"
For Windows, there is argument winslash which you might want to set all the time as it is ignored on anything other than Windows so won't affect other OSes:
> normalizePath("./foo.R", winslash="\\")
[1] "/home/gavin/tmp/bar/foo.R"
(You need to escape the \ hence the \\) or
> normalizePath("./foo.R", winslash="/")
[1] "/home/gavin/tmp/bar/foo.R"
depending on how you want the path presented/used. The former is the default ("\\") so you could stick with that if it suffices, without needing to set anything explicitly.
On R 2.13.0 then the "~/file.ext" bit also works (see comments):
> normalizePath("~/foo.R")
[1] "/home/gavin/foo.R"
I think I kind of miss the point of your question, but hopefully my answer can point you into the direction you want (it integrates your idea of using paste and getwdwith list.files):
paste(getwd(),substr(list.files(full.names = TRUE), 2,1000), sep ="")
Edit: Works on windows in some tested folders.
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