如何使用sys.path.append在python中导入文件？

Question

There are two directories on my desktop, DIR1 and DIR2 which contain the following files:

DIR1:
file1.py

DIR2:
file2.py  myfile.txt

The files contain the following:

file1.py

import sys

sys.path.append('.')
sys.path.append('../DIR2')

import file2

file2.py

import sys

sys.path.append( '.' )
sys.path.append( '../DIR2' )

MY_FILE = "myfile.txt"

myfile = open(MY_FILE) 

myfile.txt

some text

Now, there are two scenarios. The first works, the second gives an error.

Scenario 1

I cd into DIR2 and run file2.py and it runs no problem.

Scenario 2

I cd into DIR1 and run file1.py and it throws an error:

Traceback (most recent call last):
  File "<absolute-path>/DIR1/file1.py", line 6, in <module>
    import file2
  File "../DIR2/file2.py", line 9, in <module>
    myfile = open(MY_FILE)
IOError: [Errno 2] No such file or directory: 'myfile.txt'

However, this makes no sense to me, since I have appended the path to file1.py using the command sys.path.append('../DIR2') .

Why does this happen when file1.py , when file2.py is in the same directory as myfile.txt yet it throws an error? Thank you.

Answer 1

You can create a path relative to a module by using a module's __file__ attribute. For example:

myfile = open(os.path.join(
    os.path.dirname(__file__),
    MY_FILE))

This should do what you want regardless of where you start your script.

Answer 2

Replace

MY_FILE = "myfile.txt"
myfile = open(MY_FILE) 

with

MY_FILE = os.path.join("DIR2", "myfile.txt")
myfile = open(MY_FILE) 

That's what the comments your question has are referring to as the relative path solution. This assumes that you're running it from the dir one up from myfile.txt... so not ideal.

If you know that my_file.txt is always going to be in the same dir as file2.py then you can try something like this in file2..

from os import path

fname =  path.abspath(path.join(path.dirname(__file__), "my_file.txt"))
myfile = open(fname)