How to import a Python class that is in a directory above

Question

I want to inherit from a class in a file that lies in a directory above the current one   Is it possible to relatively import that file

User · Answer

import sys sys path append         Adds higher directory to python modules path

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from   subpkg2 import mod  Per the Python docs  When inside a package hierarchy  use two dots  as the import statement doc says      When specifying what module to import you do not have to specify the absolute name of the module  When a module or package is contained within another package it is possible to make a relative import within the same top package without having to mention the package name  By using leading dots in the specified module or package after from you can specify how high to traverse up the current package hierarchy without specifying exact names  One leading dot means the current package where the module making the import exists  Two dots means up one package level  Three dots is up two levels  etc  So if you execute from   import mod from a module in the pkg package then you will end up importing pkg mod  If you execute from   subpkg2 import mod from within pkg subpkg1 you will import pkg subpkg2 mod  The specification for relative imports is contained within PEP 328    PEP 328 deals with absolute relative imports

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Import module from a directory which is exactly one level above the current directory   from    import module

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gimel s answer is correct if you can guarantee the package hierarchy he mentions  If you can t -- if your real need is as you expressed it  exclusively tied to directories and without any necessary relationship to packaging -- then you need to work on   file   to find out the parent directory  a couple of os path dirname calls will do -   then  if that directory is not already on sys path  prepend temporarily insert said dir at the very start of sys path    import    remove said dir again -- messy work indeed  but   when you must  you must   and Pyhon strives to never stop the programmer from doing what must be done -- just like the ISO C standard says in the  Spirit of C  section in its preface -    Here is an example that may work for you   import sys import os path sys path append      os path abspath os path join os path dirname   file     os path pardir     import module in parent dir

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How to load a module that is a directory up preface  I did a substantial rewrite of a previous answer with the hopes of helping ease people into python s ecosystem  and hopefully give everyone the best change of success with python s import system  This will cover relative imports within a package  which I think is the most probable case to OP s question  Python is a modular system This is why we write import foo to load a module  quot foo quot  from the root namespace  instead of writing  foo   dict       please avoid doing this with open os path join os path dirname   file         foo py   as foo fh     please avoid doing this     exec compile foo fh read     foo py    exec    foo     please avoid doing this  Python isn t coupled to a file-system This is why we can embed python in environment where there isn t a defacto filesystem without providing a virtual one  such as Jython  Being decoupled from a filesystem lets imports be flexible  this design allows for things like imports from archive zip files  import singletons  bytecode caching  cffi extensions  even remote code definition loading  So if imports are not coupled to a filesystem what does  quot one directory up quot  mean  We have to pick out some heuristics but we can do that  for example when working within a package  some heuristics have already been defined that makes relative imports like  foo and   foo work within the same package  Cool  If you sincerely want to couple your source code loading patterns to a filesystem  you can do that  You ll have to choose your own heuristics  and use some kind of importing machinery  I recommend importlib Python s importlib example looks something like so  import importlib util import sys    For illustrative purposes  file path   os path join os path dirname   file         foo py   module name    foo   foo spec   importlib util spec from file location module name  file path    foo spec is a ModuleSpec specifying a SourceFileLoader foo module   importlib util module from spec foo spec  sys modules module name    foo module foo spec loader exec module foo module   foo   sys modules module name    foo is the sys modules  foo   singleton  Packaging There is a great example project available officially here  https   github com pypa sampleproject A python package is a collection of information about your source code  that can inform other tools how to copy your source code to other computers  and how to integrate your source code into that system s path so that import foo works for other computers  regardless of interpreter  host operating system  etc  Directory Structure Lets have a package name foo  in some directory  preferably an empty directory   some directory      foo py     if   name       quot   main   quot     lives here  My preference is to create setup py as sibling to foo py  because it makes writing the setup py file simpler  however you can write configuration to change redirect everything setuptools does by default if you like  for example putting foo py under a  quot src  quot  directory is somewhat popular  not covered here  some directory      foo py     setup py       usr bin env python3   setup py  import setuptools  setuptools setup      name  quot foo quot               py modules   foo         python3 -m pip install --editable       or path to some directory    quot editable quot  aka -e will yet-again redirect the importing machinery to load the source files in this directory  instead copying the current exact files to the installing-environment s library  This can also cause behavioral differences on a developer s machine  be sure to test your code  There are tools other than pip  however I d recommend pip be the introductory one    I also like to make foo a  quot package quot   a directory containing   init   py  instead of a module  a single  quot  py quot  file   both  quot packages quot  and  quot modules quot  can be loaded into the root namespace  modules allow for nested namespaces  which is helpful if we want to have a  quot relative one directory up quot  import  some directory      foo            init   py     setup py       usr bin env python3   setup py  import setuptools  setuptools setup      name  quot foo quot               packages   foo       I also like to make a foo   main   py  this allows python to execute the package as a module  eg python3 -m foo will execute foo   main   py as   main    some directory      foo            init   py           main   py     if   name       quot   main   quot     lives here   def main     too      setup py       usr bin env python3   setup py  import setuptools  setuptools setup      name  quot foo quot               packages   foo                entry points            console scripts                    quot foo quot  will be added to the installing-environment s text mode shell  eg  bash -c foo               foo foo   main   main                       Lets flesh this out with some more modules  Basically  you can have a directory structure like so  some directory      bar py              import bar      foo            init   py     import foo            main   py         baz py          import foo baz         spam                           init   py     import foo spam              eggs py         import foo spam eggs      setup py  setup py conventionally holds metadata information about the source code within  such as   what dependencies are needed to install named  quot install requires quot  what name should be used for package management  install uninstall  quot name quot    I suggest this match your primary python package name in our case foo  though substituting underscores for hyphens is popular licensing information maturity tags  alpha beta etc   audience tags  for developers  for machine learning  etc   single-page documentation content  like a README   shell names  names you type at user shell like bash  or names you find in a graphical user shell like a start menu   a list of python modules this package will install  and uninstall  a defacto  quot run tests quot  entry point python   setup py test  Its very expansive  it can even compile c extensions on the fly if a source module is being installed on a development machine  For a every-day example I recommend the PYPA Sample Repository s setup py If you are releasing a build artifact  eg a copy of the code that is meant to run nearly identical computers  a requirements txt file is a popular way to snapshot exact dependency information  where  quot install requires quot  is a good way to capture minimum and maximum compatible versions  However  given that the target machines are nearly identical anyway  I highly recommend creating a tarball of an entire python prefix  This can be tricky  too detailed to get into here  Check out pip install s --target option  or virtualenv aka venv for leads  back to the example how to import a file one directory up  From foo spam eggs py  if we wanted code from foo baz we could ask for it by its absolute namespace  import foo baz  If we wanted to reserve capability to move eggs py into some other directory in the future with some other relative baz implementation  we could use a relative import like  import   baz

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Here s a three-step  somewhat minimalist version of ThorSummoner s answer for the sake of clarity  It doesn t quite do what I want  I ll explain at the bottom   but it works okay  Step 1  Make directory and setup py filepath to project name      setup py  In setup py  write  import setuptools  setuptools setup name  project name    Step 2  Install this directory as a package Run this code in console  python -m pip install --editable filepath to project name  Instead of python  you may need to use python3 or something  depending on how your python is installed  Also  you can  use -e instead of --editable  Now  your directory will look more or less like this  I don t know what the egg stuff is  filepath to project name      setup py     test 3 egg-info          dependency links txt         PKG-INFO         SOURCES txt         top level txt  This folder is considered a python package and you can import from files in this parent directory even if you re writing a script anywhere else on your computer  Step 3  Import from above Let s say you make two files  one in your project s main directory and another in a sub directory  It ll look like this  filepath to project name      top level file py     subdirectory          subfile py      setup py                test 3 egg-info    ----- Ignore these guys                          Now  if top level file py looks like this  x   1  Then I can import it from subfile py  or really any other file anywhere else on your computer    subfile py  OR  some other python file somewhere else py  import random   This is a standard package that can be imported anywhere  import top level file   Now  top level file py works similarly   print top level file x   This is different than what I was looking for  I hoped python had a one-line way to import from a file above  Instead  I have to treat the script like a module  do a bunch of boilerplate  and install it globally for the entire python installation to have access to it  It s overkill  If anyone has a simpler method than doesn t involve the above process or importlib shenanigans  please let me know

User · Answer

Python is a modular system  Python doesn t rely on a file system  To load python code reliably  have that code in a module  and that module installed in python s library   Installed modules can always be loaded from the top level namespace with import  lt name gt     There is a great sample project available officially here  https   github com pypa sampleproject  Basically  you can have a directory structure like so   the foo project      setup py        bar py              import bar      foo          init   py       import foo         baz py            import foo baz         faz               import foo faz            init   py         daz py          import foo faz daz      etc       Be sure to declare your setuptools setup   in setup py    official example  https   github com pypa sampleproject blob master setup py  In our case we probably want to export bar py and foo   init   py  my brief example   setup py     usr bin env python3  import setuptools  setuptools setup              py modules   bar        packages   foo                entry points                Note  any changes to your setup py  like adding to  packages   or           changing  entry points  will require the module to be reinstalled             python3 -m pip install --upgrade --editable   the foo project        Now we can install our module into the python library  with pip  you can install the foo project into your python library in edit mode   so we can work on it in real time  python3 -m pip install --editable   the foo project    if you get a permission error  you can always use     pip     --user  to install in your user python library      Now from any python context  we can load our shared py modules and packages          foo script py     usr bin env python3  import bar import foo  print dir bar   print dir foo

[python] How to import a Python class that is in a directory above?

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