Check existence of directory and create if doesn t exist

Question

I often find myself writing R scripts that generate a lot of output  I find it cleaner to put this output into it s own directory s   What I ve written below will check for the existence of a directory and move into it  or create the directory and then move into it  Is there a better way to approach this   mainDir  lt -  c  path to main dir  subDir  lt -  outputDirectory   if  file exists subDir        setwd file path mainDir  subDir     else       dir create file path mainDir  subDir       setwd file path mainDir  subDir

User · Answer

As of April 16  2015  with the release of R 3 2 0 there s a new function called dir exists    To use this function and create the directory if it doesn t exist  you can use   ifelse  dir exists file path mainDir  subDir    dir create file path mainDir  subDir    FALSE    This will return FALSE if the directory already exists or is uncreatable  and TRUE if it didn t exist but was succesfully created    Note that to simply check if the directory exists you can use  dir exists file path mainDir  subDir

User · Answer

I had an issue with R 2 15 3 whereby while trying to create a tree structure recursively on a shared network drive I would get a permission error   To get around this oddity I manually create the structure   mkdirs  lt - function fp        if  file exists fp             mkdirs dirname fp           dir create fp            mkdirs  H  foo bar

User · Answer

The use of file exists   to test for the existence of the directory is a problem in the original post   If subDir included the name of an existing file  rather than just a path   file exists   would return TRUE  but the call to setwd   would fail because you can t set the working directory to point at a file   I would recommend the use of file test op  -d   subDir   which will return  TRUE  if subDir is an existing directory  but FALSE if subDir is an existing file or a non-existent file or directory   Similarly  checking for a file can be accomplished with op  -f    Additionally  as described in another comment  the working directory is part of the R environment and should be controlled by the user  not a script   Scripts should  ideally  not change the R environment   To address this problem  I might use options   to store a globally available directory where I wanted all of my output     So  consider the following solution  where someUniqueTag is just a programmer-defined prefix for the option name  which makes it unlikely that an option with the same name already exists    For instance  if you were developing a package called  filer   you might use filer mainDir and filer subDir      The following code would be used to set options that are available for use later in other scripts  thus avoiding the use of setwd   in a script   and to create the folder if necessary   mainDir    c  path to main dir  subDir    outputDirectory   options someUniqueTag mainDir   mainDir  options someUniqueTag subDir    subDir    if   file test  -d   file path mainDir  subDir      if file test  -f   file path mainDir  subDir         stop  Path can t be created because a file with that name already exists        else       dir create file path mainDir  subDir           Then  in any subsequent script that needed to manipulate a file in subDir  you might use something like   mainDir   getOption someUniqueTag mainDir  subDir   getOption someUniqueTag subDir  filename    fileToBeCreated txt  file create file path mainDir  subDir  filename     This solution leaves the working directory under the control of the user

User · Answer

Here s the simple check  and creates the dir if doesn t exists      Provide the dir name i e sub dir  that you want to create under main dir  output dir  lt - file path main dir  sub dir   if   dir exists output dir    dir create output dir    else       print  Dir already exists

User · Answer

Use showWarnings   FALSE   dir create file path mainDir  subDir   showWarnings   FALSE  setwd file path mainDir  subDir     dir create   does not crash if the directory already exists  it just prints out a warning  So if you can live with seeing warnings  there is no problem with just doing this   dir create file path mainDir  subDir   setwd file path mainDir  subDir

User · Answer

I know this question was asked a while ago  but in case useful  the here package is really helpful for not having to reference specific file paths and making code more portable   It will automatically define your working directory as the one that your  Rproj file resides in  so the following will often suffice without having to define the file path to your working directory  library here   if   dir exists here outputDir     dir create here outputDir

User · Answer

To find out if a path is a valid directory try   file info cacheDir  1  isdir     file info does not care about a slash on the end   file exists on Windows will fail for a directory if it ends in a slash  and succeeds without it  So this cannot be used to determine if a path is a directory    file exists  R  data CCAM CCAMC160b echam5 A2-ct-uf -5t05N 190to240E level1000 cache     1  FALSE  file exists  R  data CCAM CCAMC160b echam5 A2-ct-uf -5t05N 190to240E level1000 cache    1  TRUE  file info cacheDir   isdir

User · Answer

In terms of general architecture I would recommend the following structure with regard to directory creation  This will cover most potential issues and any other issues with directory creation will be detected by the dir create call   mainDir  lt -     subDir  lt -  outputDirectory   if  file exists paste mainDir  subDir       sep        collapse                cat  subDir exists in mainDir and is a directory     else if  file exists paste mainDir  subDir  sep        collapse                cat  subDir exists in mainDir but is a file         you will probably want to handle this separately   else       cat  subDir does not exist in mainDir - creating       dir create file path mainDir  subDir      if  file exists paste mainDir  subDir       sep        collapse                  By this point  the directory either existed or has been successfully created     setwd file path mainDir  subDir     else       cat  subDir does not exist         Handle this error as appropriate     Also be aware that if   foo doesn t exist then a call to dir create    foo bar   will fail unless you specify recursive   TRUE

User · Answer

One-liner   if   dir exists output dir    dir create output dir    Example   dateDIR  lt - as character Sys Date    outputDIR  lt - file path outD  dateDIR  if   dir exists outputDIR    dir create outputDIR

[r] Check existence of directory and create if doesn't exist

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