adding directory to sys.path /PYTHONPATH


I am trying to import a module from a particular directory.

The problem is that if I use sys.path.append(mod_directory) to append the path and then open the python interpreter, the directory mod_directory gets added to the end of the list sys.path. If I export the PYTHONPATH variable before opening the python interpreter, the directory gets added to the start of the list. In the latter case I can import the module but in the former, I cannot.

Can somebody explain why this is happening and give me a solution to add the mod_directory to the start, inside a python script ?

12/16/2017 11:00:32 PM

Accepted Answer

This is working as documented. Any paths specified in PYTHONPATH are documented as normally coming after the working directory but before the standard interpreter-supplied paths. sys.path.append() appends to the existing path. See here and here. If you want a particular directory to come first, simply insert it at the head of sys.path:

import sys

That said, there are usually better ways to manage imports than either using PYTHONPATH or manipulating sys.path directly. See, for example, the answers to this question.

5/23/2017 12:18:20 PM

As to me, i need to caffe to my python path. I can add it's path to the file /home/xy/.bashrc by add

export PYTHONPATH=/home/xy/caffe-master/python:$PYTHONPATH.

to my /home/xy/.bashrc file.

But when I use pycharm, the path is still not in.

So I can add path to PYTHONPATH variable, by run -> edit Configuration.

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