Python Packages

By Mr. PRR

PRR TECHNOLOGIES 25-05-2021 1

 Python Packages
• Modules are files containing Python statements and definitions, like function
and class definitions.
• A package is basically a directory with Python files and a file with the name
__init__.py. This means that every directory inside of the Python path,
which contains a file named __init__.py, will be treated as a package by
Python.
• It's possible to put several modules into a Package.

PRR TECHNOLOGIES 25-05-2021 2

 __init__.py

PRR TECHNOLOGIES 25-05-2021 3

 Create A Package
• Create a new folder named D:\MyApp.
• Inside MyApp, create a subfolder with the name 'mypackage'.
• Create an empty __init__.py file in the mypackage folder.
• Create modules greet.py and functions.py
• We have created our package called mypackage with two modules and one
file.

PRR TECHNOLOGIES 25-05-2021 4

PRR TECHNOLOGIES 25-05-2021 5
 Mypackage files
greet.py functions.py __init__ .py:
def SayHello(name): def sum(x,y): pass
print("Hello ", name) return x+y
def average(x,y):
return (x+y)/2
def power(x,y):
return x**y
PRR TECHNOLOGIES 25-05-2021 6
 Importing a Module from a Package
• We can import modules from package by using import keyword. Here we are
Importing the functions module from the mypackage package and call its
power() function.
• Ex:
• >>> from mypackage import functions
>>> functions.power(3,2)
9

PRR TECHNOLOGIES 25-05-2021 7

 It is also possible to import specific
functions from a module in the package.
>>> from mypackage.functions import sum
>>> sum(10,20)
30
>>> average(10,12)
Traceback (most recent call last):
File "<pyshell#13>", line 1, in <module>
NameError: name 'average' is not defined
PRR TECHNOLOGIES 25-05-2021 8
 __init__.py
• Python defines two types of packages, regular packages and namespace packages.
• Regular packages are traditional packages as they existed in Python 3.2 and earlier.
• A regular package is typically implemented as a directory containing an __init__.py
file.
• When a regular package is imported, this __init__.py file is implicitly executed, and
the objects it defines are bound to names in the package’s namespace.
• The __init__.py file can contain the same Python code that any other module can
contain, and Python will add some additional attributes to the module when it is
imported.
PRR TECHNOLOGIES 25-05-2021 9
 Install a Package Globally
• Once a package is created, it can be installed for system-wide use by running the
setup script. The script calls setup() function from the setuptools module.
• Let's install mypackage for system-wide use by running a setup script.
• Save the setup code as setup.py in the parent folder MyApp. The script calls the
setup() function from the setuptools module. The setup() function takes various
arguments such as name, version, author, list of dependencies, etc.
• The zip_safe argument defines whether the package is installed in compressed
mode or regular mode.
PRR TECHNOLOGIES 25-05-2021 10
 setup.py
from setuptools import setup
setup(name='mypackage',
version='0.1',
description='Testing installation of Package',
url='#',
author='auth',
author_email='author@email.com',
license='MIT',
packages=['mypackage'],
zip_safe=False)
PRR TECHNOLOGIES 25-05-2021 11
• Now execute the following command to install mypackage using the pip
utility. Ensure that the command prompt is in the parent folder, in this case
D:\MyApp.
• D:\MyApp>pip install mypackage
Processing d:\MyApp
Installing collected packages: mypack
Running setup.py install for mypack ... done
Successfully installed mypackage-0.1
• Now mypackage is available for system-wide use and can be imported in any
script or interpreter.

PRR TECHNOLOGIES 25-05-2021 12

Ex:
• D:\>python
>>> import mypackage
>>>mypackage.average(10,20)
15.0
>>>mypackage.power(10,2)
100

PRR TECHNOLOGIES 25-05-2021 13

 PyPI - Python Package Index
• PyPI is the default repository of Python packages for Python community
that includes frameworks, tools and, libraries.
• Python developers can install and use packages in the Python application.
• It is open to all Python developers to consume and distribute their
distributions.
• Developers can search or browse projects from pypi.org.

PRR TECHNOLOGIES 25-05-2021 14

 Install pip
• PIP has been included with Python installer since Python 3.4. You can verify
whether the pip is installed on your machine by running the following command in
your console:
C:\Users\PRR TECHNOLOGIES> pip --version
pip 20.2.3 from c:\users\prr
technologies\appdata\local\programs\python\python39\lib\site-packages\pip
(python 3.9)

PRR TECHNOLOGIES 25-05-2021 15

• If you are using an older version of pip, you can upgrade pip by running the
following command on Windows:
C:\> python -m pip install -U pip
• Execute the following command on Linux or Mac OS to upgrade pip:
$ pip install -U pip

PRR TECHNOLOGIES 25-05-2021 16

• If pip isn't already installed, then first try to bootstrap it from the standard library
by executing the following command in your console or terminal window:
python -m ensurepip --default-pip
• If that still doesn't install pip, the following steps should install pip on your
platform.
o Download get-pip.py from https://bootstrap.pypa.io/get-pip.py and save it to
your local folder.
o Navigate command prompt or terminal to the folder where you have
downloaded the file and run the command: python get-pip.py
• This command will install pip in your pc. Additionally, it also installs the wheel and
setuptools.
PRR TECHNOLOGIES 25-05-2021 17
 pip Help command
• The pip help command is used to get a list of all the functions available in pip.
C:\Users\PRR TECHNOLOGIES>pip help
Usage:
pip <command> [options]
Commands:
install Install packages.
download Download packages.
Etc…
PRR TECHNOLOGIES 25-05-2021 18
 Installing packages
• PyPI maintains packages as projects. Use the following pip command to install the
latest version of the project.
Pip install "project-name"
• Use the following command installs the specific version of the project:
pip install "project-name==2.4"
• Use the following command to install a version that's "compatible" with a certain
version:
pip install "project-name~=2.4"
PRR TECHNOLOGIES 25-05-2021 19
 List packages
• The list command can be used to see all the packages that have been installed on the
system. If you want to check all the packages, use the pip list command:
C:\Users\PRR TECHNOLOGIES>pip list
Package Version
---------- -------
cx-Oracle 8.1.0
pip 20.2.3
PRR 1.0
setuptools 49.2.1
PRR TECHNOLOGIES 25-05-2021 20
 Show package
• If you want to check the metadata of a package, then use pip show command. The following
command will display the metadata of the urllib3 package.
C:\Users\PRR TECHNOLOGIES>pip show cx-Oracle
Name: cx-Oracle
Version: 8.1.0
Summary: Python interface to Oracle
Home-page: https://oracle.github.io/python-cx_Oracle
Author: "Anthony Tuininga",
Author-email: "anthony.tuininga@gmail.com",
License: BSD License
Location: c:\users\prr technologies\appdata\local\programs\python\python39\lib\site-
packages
PRR TECHNOLOGIES 25-05-2021 21
 Uninstalling a Package
• The pip uninstall command can be used to remove a package. For example,
if you want to remove urllib3 package, you can simply use the following
command:
• $ pip uninstall urllib3
• The pip package manager will ask you to confirm if you want to uninstall the
package. Proceed (y/n)?: If you press y, the package will be removed.
• Thus, you can use pip as a package manager of your Python application.
PRR TECHNOLOGIES 25-05-2021 22