Why Can't Python Find Shared Objects That Are in Directories in Sys.Path

Python can't find module in the same folder

Your code is fine, I suspect your problem is how you are launching it.

You need to launch python from your '2014_07_13_test' directory.

Open up a command prompt and 'cd' into your '2014_07_13_test' directory.

For instance:

$ cd /path/to/2014_07_13_test
$ python test.py

If you cannot 'cd' into the directory like this you can add it to sys.path

In test.py:

import sys, os
sys.path.append('/path/to/2014_07_13_test')

Or set/edit the PYTHONPATH

And all should be well...

...well there is a slight mistake with your 'shebang' lines (the first line in both your files), there shouldn't be a space between the '#' and the '!'

There is a better shebang you should use.

Also you don't need the shebang line on every file... only the ones you intend to run from your shell as executable files.

Importing modules from parent folder

It seems that the problem is not related to the module being in a parent directory or anything like that.

You need to add the directory that contains ptdraft to PYTHONPATH

You said that import nib worked with you, that probably means that you added ptdraft itself (not its parent) to PYTHONPATH.

Expand Python Search Path to Other Source

There are a few possible ways to do this:

  • Set the environment variable PYTHONPATH to a colon-separated list of directories to search for imported modules.
  • In your program, use sys.path.append('/path/to/search') to add the names of directories you want Python to search for imported modules. sys.path is just the list of directories Python searches every time it gets asked to import a module, and you can alter it as needed (although I wouldn't recommend removing any of the standard directories!). Any directories you put in the environment variable PYTHONPATH will be inserted into sys.path when Python starts up.
  • Use site.addsitedir to add a directory to sys.path. The difference between this and just plain appending is that when you use addsitedir, it also looks for .pth files within that directory and uses them to possibly add additional directories to sys.path based on the contents of the files. See the documentation for more detail.

Which one of these you want to use depends on your situation. Remember that when you distribute your project to other users, they typically install it in such a manner that the Python code files will be automatically detected by Python's importer (i.e. packages are usually installed in the site-packages directory), so if you mess with sys.path in your code, that may be unnecessary and might even have adverse effects when that code runs on another computer. For development, I would venture a guess that setting PYTHONPATH is usually the best way to go.

However, when you're using something that just runs on your own computer (or when you have nonstandard setups, e.g. sometimes in web app frameworks), it's not entirely uncommon to do something like

import sys
from os.path import dirname
sys.path.append(dirname(__file__))


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