I've been writing in python for a couple of months now and I've never found a through explanation of how import works. I downloaded this folder with subfolders with python files in them. I'm trying to use one of these files and I'm loosing my mind. How do you properlly import a folder with all the files in it?
Any help would be greatly appreciated.
As written in the python documentation on modules:
If you have a folder sound looking like that :
sound/ Top-level package
__init__.py Initialize the sound package
effects/ Subpackage for sound effects
__init__.py
echo.py
surround.py
reverse.py
To import all files of effects folder :
from sound.effects import *
Note that to be able to import module, they have to contain an __init__.py file.
First, check to see if the subdirectories have a file named __init__.py file in them. Python will not recognize directories that do not contain these files.
Then, you will have to manually change the PYTHONPATH, which you can find in sys.path. You can find a great example here.
Edit: I'm not 100% sure this is what you were asking for. If you want to import ALL the python files in a directory, you will have to import them one by one. For example, given a directory like so:
parent/
__init__.py
runner.py
example.py
language.py
you would have to type
from parent import runner, example, language
or
from parent import * # this will also import __init__
You have to create a __init__.py file in the directory to make it a package. In this file you import all the symbols from the underlying files.
See http://docs.python.org/tutorial/modules.html (especially part 6.4 Packages) for further notes on that.
The parent folder must be either in PYTHONPATH or the folder path indicated in a file with extension .pth situated in a location in your path, usually in site-packages.
Then your package and all folders inside it from which you have to import need to have a file named __init__. This file can be used for program initialization but as a starting point it can be an empty file.
For example my program folder, situated in C:\python26 has the estructure:
programas\
.....package1\
.........__init__.py
.........module1.py
.........subpackage1\
.............__init__.py
.............module2.py
.....package2\
.........__init__.py
.........module3
.....__init__.py
.....lonelyscript1.py
.....lonelyscript2.py
file site-packages\site.pth contains:
C:\Python26\programas
Related
I am trying to import a module from a python file that is in a sibling folder. I read several similar questions here and tried to apply solutions listed there, but I wasn't able to solve the problem.
The structure is as follows:
parentfolder/gfolder/codefolder/fileA.py
parentfolder/gfolder/utilfolder/util.py
gfolder, codefolder and utilfolder all have an __init__.py.
I'm trying to do in fileA.py:
import gfolder.utilfolder.util as util
I also tried adding before the import statement:
sys.path.append(".../parentfolder/")
And that didn't work either:
import gfolder.utilfolder.util as util
ModuleNotFoundError: No module named 'gfolder'
The solution in a similar question says to include __init.py__ in the directories, which I already have.
EDIT:
Now both sys.append and sys.insert work and the problem was that I included a slash at the end of the path. When I took it out, everything worked.
First of all, let me describe you the differences between a Python module & a Python package so that both of us are on the same page. ✌
A module is a single .py file (or files) that are imported under one import and used. ✔
import aModuleName
# Here 'aModuleName' is just a regular .py file.
Whereas, a package is a collection of modules in directories that give a package hierarchy. A package contains a distinct __init__.py file. ✔
from aPackageName import aModuleName
# Here 'aPackageName` is a folder with a `__init__.py` file
# and 'aModuleName', which is just a regular .py file.
Therefore, when we have a project directory named proj-dir of the following structure ⤵
proj-dir
--|--__init__.py
--package1
--|--__init__.py
--|--module1.py
--package2
--|--__init__.py
--|--module2.py
🔎 Notice that I've also added an empty __init__.py into the proj-dir itself which makes it a package too.
👍 Now, if you want to import any python object from module2 of package2 into module1 of package1, then the import statement in the file module1.py would be
from proj-dir.package2.module2 import object2
# if you were to import the entire module2 then,
from proj-dir.package2 import module2
I hope this simple explanation clarifies your doubts on Python imports' mechanism. 😊
As Andrew Cox answerd int the following thread Import a module from a relative path
You can add the subdirectory to your Python path so that it imports as a normal script
import sys
sys.path.insert(0, <path to gfolder>)
import gfolder
you can also add the directory to the PATH var of the Linux system (I use it while I'm working on a project, at the end i modified the PATH to it's origin value)
if you maintain the following structre than it is working out side the box
parentfolder/gfolder/codefolder/fileA.py
parentfolder/gfolder/utilfolder/util.py
parentfolder/gfolder/main.py
run main.py
I busy with some calculations in Python and therefore i have some bunch of scripts.
I have tried to clean this up thru 2 folders named scripts and tests.
Now i have the problem that my main Python file don't recognize the scripts in the subfolders.
So my import filename don't work anny more. When i look in some git files it looks like the don mention paths and still it works.
I had looked at this SE question but that gave me a error (ImportError: No module named "filename")
What have i to do in my main script, subfolder or files in subfolders.
my scripts are no classes yet... Probably not all become classes. so a generic solution is best
You can do relative imports from where you are. Let's assume you're importing from the file /home/janbert/projects/test/test.py
If you want to import /home/janbert/projects/test/subdir/file.py you write:
from subdir import file
And if you want to import /home/janbert/projects/otherproject/subdir/file.py you write:
from ..otherproject.subdir import file
Just remember that each python package (ie folder) must have a file named __init__.py (which can be empty), otherwise you can not import from that package.
I use
sys.path.append('D:/my_library_folder/')
import mymodule
in order to import some module.
How to add permanently this folder D:/my_library_folder/ to the Python library path, so that I will be able to use only
import mymodule
in the future?
(Even after a reboot, etc.)
just put the folder in site-packages directory. ie:
C:\PythonXY\Lib\site-packages
Note: you need to add an empty file __init__.py to the folder
Files named __init__.py are used to mark directories on disk as a Python package directories.
If you have the files:
C:\PythonXY\Lib\site-packages\<my_library_folder>\__init__.py
C:\PythonXY\Lib\site-packages\<my_library_folder>\module.py
you can import the code in module.py as:
from <my_library_folder> import module
If you remove the __init__.py file, Python will no longer look for submodules inside that directory, so attempts to import the module will fail.
If you have lots of folders, then create the empty __init__.py file in each folder. for eg:
C:\PythonXY\Lib\site-packages\<my_library_folder>\
__init__.py
module.py
subpackage\
__init__.py
submodule1.py
submodule2.py
Set PYTHONPATH environment variable to D:/my_library_folder/
If D:/my_library_folder is a project you're working on and has a setup script, you could also do python setup.py develop. Not entirely related to the question, but I also recommend using virtualenv.
Here is my file structure that I am working with for my application. My problem is that I cannot get my test_ctd.py file to see my ctd.py file.
Here is my directory structure
FileParser
--Parsers
----ctd.py
--tests
----__init__.py
----test_ctd.py
--parse.py
I never used an init.py file and am struggling to understand it, but here is my attempt at adding ctd.py to my path.
import sys
import os.path
d = os.path.dirname(os.path.dirname(os.path.abspath('../../')))
from Parsers import ctd
Also I do not have any code in my parse.py file, but I will be using that to initiate the program. Would I need a init file for that as well so I can import the files from the Parsers folder?
Any help on how to access my files from within this program structure would be appreciated. Eventually it will be running on a web server, not sure if that makes a difference or not...
Thanks!
Parsers and FileParser must contain __init__.py if you want to import something from ctd.py. See Importing modules in Python and __init__.py.
Then, you can import ctd.py from your tests scripts by doing relative imports like from ..Parsers import ctd or by adding FileParser to sys.path and using from Parsers import ctd.
Or, add the directory containing FileParser to sys.path and use from FileParser.Parsers import ctd.
Hope that helps.
You need to make sure Python is actually looking in the right places. You can do this by modifying your PYTHONPATH environment variable to include places where Python packages are found (such as this directory). You'll also need an __init__.py file, to mark the directory as a Python package.
Or, the cheap, hacky way is by modifying sys.path.
import sys
import os
sys.path.insert(0, os.path.join(os.path.abspath(os.path.dirname(__file__)), 'Parsers'))
import cdt
Move the __init__.py file into Parsers and add the directory FileParser as absolute path to your PYTHONPATH. For example with sys.path.append('full/path/to/FileParser').
I did some websearch, but all I found was frustration.
I have a project in a directory (lets call it) "projectdir", in which I have "main.py".
In projectdir I have a subdirectory called "otherstuff", In which I have "foo.py".
How do I import foo.py, so I can use its contents in main.py, without doing much of the work that python designers/implementors should have, and without relying on boilerplate files?
Or is that impossible in python?
You need to put a __init__.py file in otherstuff subdirectory, to mark it as a package. After, you can import your module using:
import subdirectory.foo
or
from subdirectory import foo
The __init__.py file can be empty. There is no other "clean" way to achieve that in python.
you need to include __init__.py in your otherstuff directory. This is to tell python to search there for imports.
The python documentation explains how the module/package import works. And is def worth the time reading it, despite its kind of long length