How do I get the absolute path of an input file in R

Question

I am using Rscript to plot some figures from a given CSV file in some directory, which is not necessarily my current working directory. I can call it as follows:

./script.r ../some_directory/inputfile.csv 

Now I want to output my figures in the same directory (../some_directory), but I have no idea how to do that. I tried to get the absolute path for the input file because from this I could construct the output path, but I couldn't find out how to do that.

Answer 1

normalizePath() #Converts file paths to canonical user-understandable form 

or

library(tools) file_path_as_absolute() 

Answer 2

The question is very old but it still misses a working solution. So here is my answer:

Use normalizePath(dirname(f)). The example below list all the files and directories in the current directory.

dir <- "." allFiles <- list.files(dir) for(f in allFiles){   print(paste(normalizePath(dirname(f)), fsep = .Platform$file.sep, f, sep = ""))  } 

Where:

• normalizePath(dirname(f)) gives the absolute path of the parent directory. So the individual file names should be added to the path.
• .Platform is used to have an OS-portable code. (here)
• file.sep gives "the file separator used on your platform: "/" on both Unix-alikes and on Windows (but not on the former port to Classic Mac OS)." (here)

---

Warning: This may cause some problems if not used with caution. For instance, say this is the path: A/B/a_file and the working directory is now set to B. Then the code below:

dir <- "B" allFiles <- list.files(dir) for(f in allFiles){   print(paste(normalizePath(dirname(f)), fsep = .Platform$file.sep, f, sep = ""))  } 

would give:

> A/a_file 

however, it should be:

> A/B/a_file