python package: can't import a class from working directory-CodePudding

In my current working directory is a sub-directory cpuimlearn, having the following structure:

$ tree cpuimlearn
cpuimlearn
├── AdaBoostM1.py
├── DECOC.py
├── DOAO.py
├── factory.py
├── FocalBoost.py
├── ImECOC.py
├── __init__.py
└── SAMME.py

0 directories, 8 files

The file factory.py implements a class FAC such that:

class FAC:

    def __init__(self):

        pass
    ...

So all other files import this class. For example, AdaBoostM1.py imports the class like so:

File: AdaBoostM1.py

from factory import FAC
fac = FAC()
....

Strangely however, these files cannot import the class. For example:

$ python
Python 3.8.3 (default, Jul  2 2020, 16:21:59) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 
>>> 
>>> from cpuimlearn import AdaBoostM1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "~/gpuimlearn/src/CPU-imLearn/cpuimlearn/AdaBoostM1.py", line 21, in <module>
    from factory import FAC
ModuleNotFoundError: No module named 'factory'
>>>

As can be seen from the new __pycache__ directory created, factory.cpython-38.pyc isn't created as we expect if the module was successfully imported.

This is strange since factory.py is available in the direcory, and this implements FAC class.

$ tree cpuimlearn
cpuimlearn
├── AdaBoostM1.py
├── DECOC.py
├── DOAO.py
├── factory.py
├── FocalBoost.py
├── ImECOC.py
├── __init__.py
├── __pycache__
│   ├── AdaBoostM1.cpython-38.pyc
│   └── __init__.cpython-38.pyc
└── SAMME.py

1 directory, 10 files

CodePudding user response：

As you have __init__.py in your directory, then this directory is treated as a python package. To import inside python package you need to use relative import

from .factory import FAC

or full name import

from cpuimlearn.factory import FAC

explanation from python documentation is here: https://docs.python.org/3/tutorial/modules.html

CodePudding user response：

factory is not a package.

You'd need to use relative imports:

from .factory import FAC

Alternatively: from cpuimlearn.factory import FAC