What is a Python egg?

A Python egg is a structure embodying the release of a specific version of a Python module, comprising its code, resources and metadata. It needs to be importable and discoverable.

There are two basic formats currently implemented for Python eggs:

• .egg: a directory or zipfile containing the module’s code and resources, along with a EGG-info subdirectory that contains the module’s metadata
• .egg-info: a directory contains module’s metadata.

.egg file?

How to create an egg (setup.py)?

To create an .egg file for a directory say mymath which itself may have several python scripts, do the following step

How to run the egg file?

if you have an .egg file, you can install it as a package using easy_install

egg-info?

__init__.py?

Module not found problem

Sometimes when we type import <module_1> at the interactive Python console, we see the following error ModuleNotFoundError: No module named "<module_1>.

Where does Python look for modules?

Python looks for modules in sys.path. To check sys.path, open a Python console, type

import sys
print(sys.path): returns a list of paths

To include the module’d directory inside the sys.path list, we can use one of the following methods:

1. put the directory into the contents of PYTHONPATH environment variable
2. make the module part of an installable package, and install it.

In the following sections, we discuss in details how to add a directory on the Python sys.path list.

Methods to add a module

• Method 1: Append the path to PYTHONPATH

export PYTHONPATH=<path to your package>:$PYTHONPATH

• Method2: add to .bashrc

Comments

I encounter this problem twice during my work. First time was I missed to add __init__.py in the folder. Second time is that I messed up the folder structure, and I noticed that the package name showed up in the pip list, but cause the Import Error: Module not found in the python terminal.