CODEWITHSUNDEEP
rfilepath
SeverinBang
SeverinBang

Reputation: 151

generate path from absolute and relative paths in R

Is there a fast and robust way to generate absolute paths from a mixture of absolute and relative paths in R?

More concrete, I look for a function that can (robustly) interpret the ../ operator, and returns a "recursively" followed absolute path, as for example:

rel_path_1 <- "../../path1/path2/"
rel_path_2 <- "../final/"
abs_path <- "/home/username/foo/bar/glarb/zorb"

my_function(abs_path, rel_path_1)
# "/home/username/foo/bar/path1/path2/

my_function(abs_path, rel_path_2)
# "/home/username/foo/bar/glarb/final/

my_function(abs_path, rel_path_1, rel_path_2)
# "/home/username/foo/bar/glarb/path1/final/

I thought about fiddling around something with regex and counting path separators and ../ operators to truncate the ens, but I fear the result would be less then stable.

Upvotes: 0

Views: 455

Answers (1)

Seb
Seb

Reputation: 342

What you are actually looking for is path normalization. The R package {fs} is doing this nicely. But you could also use base R. Here is your example with both solutions.

rel_path_1 <- "../../path1/path2/"
rel_path_2 <- "../final/"
abs_path <- "/home/username/foo/bar/glarb/zorb"

# using base R. mustWork = FALSE because the example uses non existent paths
normalizePath(file.path(abs_path, rel_path_1), mustWork = FALSE)
#> [1] "C:\\home\\username\\foo\\bar\\path1\\path2"

# using R package fs
fs::path_norm(fs::path(abs_path, rel_path_1))
#> /home/username/foo/bar/path1/path2

Created on 2022-01-05 by the reprex package (v2.0.1)

Upvotes: 2

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