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I met a very strange problem:

My file structure is like: (core and test are directories)

 core
    ----file1.py

    ----__init__.py

 test

    ----file2.py

in file2, i wrote: 

from core import file1

result is:

ImportError: cannot import name file1
wjxiz
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3 Answers3

2

Have to create __init__.py file inside the test dir:

Because The __init__.py files are required to make Python treat the directories as containing packages.

parent/
    child1/
        __init__.py
        file1.py

     child2/
        __init__.py
        file2.py

From the error:

If run the child2/file2.py file directly. You are not able to access child1/file1.py from the child2/file2.py

Because only from the parent directory can access the child.

If have a folder structure like:

parent/
    child1/
         __init__.py
         file1.py
    child2/
         __init__.py
         file2.py
    file3.py

If we run the file3.py file. Can able to access both child1/file1.py, child2/file2.py in file3.py
Because It is running from the parent directory.

If we need to access child1/file1 from child2/file2.py, We need to set the parent directory:

By running this below command we can achieve it...

PYTHONPATH=. python child2/file2.py

PYTHONPATH=. It refers the parent path. Then runs child2/file2.py file from the shell

Mohammed Yasin
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1

It's not a strange problem, imports simply don't work like that.

From the official documentation: https://docs.python.org/3/tutorial/modules.html

When a module named spam is imported, the interpreter first searches for a built-in module with that name. If not found, it then searches for a file named spam.py in a list of directories given by the variable sys.path. sys.path is initialized from these locations:

  • The directory containing the input script (or the current directory when no file is specified).
  • PYTHONPATH (a list of directory names, with the same syntax as the shell variable PATH).
  • The installation-dependent default.

You could look into relative imports, here's a good source: https://stackoverflow.com/a/16985066/4886716

The relevant info from that post is that there's no good way to do it unless you add core to PYTHONPATH like Shawn. L says.

Community
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Oersted
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  • hey, thanks man. I have a directory called "core-2" inside "core" ,and the python file inside core-2 can successfully import file1(file1 is in 'core' ). According to the tuto, it should not be able to do that. I misunderstand somewhere? – wjxiz May 15 '17 at 09:40
  • That does sound like it would work yes... Truth be told, I'm not sure either. Maybe the second link I posted could be of help, I think it addresses this. – Oersted May 15 '17 at 09:59
0

When I tried your case, I got

Traceback (most recent call last):
  File "file2.py", line 3, in <module>
    from core import file1
ImportError: No module named core

The reason is that Python does not find core. In this case, you need to add core to the system path, as shown below (add them at the very beginning of file2.py):

import sys,os
sys.path.append(path_to_core.py)

Or, if you would run it using command line, you could simply put the following at the beginning of file2.py

import sys,os
sys.path.append(os.path.join(os.path.dirname(__file__),'../'))

Here, os.path.join(os.path.dirname(__file__),'../') is to state the path to file2.py.

Shawn. L
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