Python PIP 4

Python Pip
In this tutorial, you will learn how to use pip to install and manage Python packages.

What is pip?
pip is the standard package manager for Python. You can use pip to install additional packages that are not available in the Python standard library. For example,

pip install numpy
If you have pip on your system, typing this command in our console or terminal would have installed the numpy library.

How to Install pip?
pip comes pre-installed on Python versions 3.4 or later. You can check if pip is installed by using the following command in the console:

pip --version
If pip is already available in the system, the respective pip version is displayed, like:

pip 22.2.2 from C:\Program Files\Python310\lib\site-packages\pip (python 3.10)
If you are using an older version of Python or do not have pip installed for some other reason, follow the steps as described in this link: pip installation.

Using pip
pip is a command-line program. After its installation, a pip command is added, which can be used with the command prompt.

The basic syntax of pip is:

pip <pip arguments>
Install Packages With pip
The Python community contributes to an extensive number of packages tailored for various development frameworks, tools, and libraries.

Most of these packages are officially hosted and published to the Python Package Index (PyPI). pip allows us to download and install these packages.

Basic Package Installation
You can use the install command to install packages using pip:

pip install <package_name>
Suppose you want to install requests, a popular HTTP library for Python. You can do it with the help of the following command:

pip install requests
Output

Collecting requests
Collecting requests
  Using cached https://files.pythonhosted.org/packages/51/bd/23c926cd341ea6b7dd0b2a00aba99ae0f828be89d72b2190f27c11d4b7fb/requests-2.22.0-py2.py3-none-any.whl
Collecting chardet=3.0.2
  Using cached https://files.pythonhosted.org/packages/bc/a9/01ffebfb562e4274b6487b4bb1ddec7ca55ec7510b22e4c51f14098443b8/chardet-3.0.4-py2.py3-none-any.whl
Collecting urllib3!=1.25.0,!=1.25.1,=1.21.1
  Using cached https://files.pythonhosted.org/packages/b4/40/a9837291310ee1ccc242ceb6ebfd9eb21539649f193a7c8c86ba15b98539/urllib3-1.25.7-py2.py3-none-any.whl
Collecting idna=2.5
  Using cached https://files.pythonhosted.org/packages/14/2c/cd551d81dbe15200be1cf41cd03869a46fe7226e7450af7a6545bfc474c9/idna-2.8-py2.py3-none-any.whl
Collecting certifi>=2017.4.17
  Downloading https://files.pythonhosted.org/packages/b9/63/df50cac98ea0d5b006c55a399c3bf1db9da7b5a24de7890bc9cfd5dd9e99/certifi-2019.11.28-py2.py3-none-any.whl (156kB)
Installing collected packages: chardet, urllib3, idna, certifi, requests
Successfully installed certifi-2019.11.28 chardet-3.0.4 idna-2.8 requests-2.22.0 urllib3-1.25.7
When installing the requests package, all other required dependencies like chardet, urllib3 and certifi are also installed by pip.

Specifying Package Version
When we just type the pip install command, pip downloads the most recent version of the package.

Sometimes, only a specific version is compatible with other programs. So, you can define the version of the package in the following way:

pip install requests==2.21.0
Here, we have installed the 2.21.0 version of the requests library.

List Installed Packages With pip
The pip list command can be used to list all the available packages in the current Python environment.

pip list
Output

Package    Version
---------- ----------
certifi    2019.11.28
chardet    3.0.4
idna       2.8
pip        19.3.1
requests   2.22.0
setuptools 45.0.0
urllib3    1.25.7
wheel      0.33.6
Package Information With pip show
The pip show command displays information about one or more installed packages. Let's look at an example:

pip show requests
Output

Name: requests
Version: 2.22.0
Summary: Python HTTP for Humans.
Home-page: http://python-requests.org
Author: Kenneth Reitz
Author-email: me@kennethreitz.org
License: Apache 2.0
Location: c:\users\dell\desktop\venv\lib\site-packages
Requires: certifi, chardet, urllib3, idna
Required-by:
Here, the show command displays information about the requests library. Notice the Requires and Required-by rows in the above output:

Requires - shows which dependencies the requests library requires.
Required-by - shows the packages that require requests library.
Uninstall a Package With pip
You can uninstall a package with the pip uninstall command.

Suppose you want to remove the requests library from our current Python environment. You can do it in the following way:

pip uninstall requests
Output

Uninstalling requests-2.22.0:
  Would remove:
    C:\Python37\lib\site-packages\requests-2.22.0.dist-info\*
    C:\Python37\lib\site-packages\requests\*
Proceed (y/n)? y
  Successfully uninstalled requests-2.22.0
As you can see, the requests package is removed after the final prompt.

Note: Even though the specified package is removed, the packages that were installed as dependencies are not removed. In this case, the dependencies (chardet, urllib3, and certifi) of the requests library aren't uninstalled.

If you need to remove the dependencies of a package as well, you can use the pip show command to view installed packages and remove them manually.

Use Requirements Files
A file containing all the package names is called a Requirements File. You can also use such files to install Python packages in batches.

Suppose you have a file requirements.txt which has the following entries:

numpy
Pillow
pygame
You can install all these packages and their dependencies using a single command in pip.

pip install -r requirements.txt
Output

Collecting numpy
  Using cached https://files.pythonhosted.org/packages/a9/38/f6d6d8635d496d6b4ed5d8ca4b9f193d0edc59999c3a63779cbc38aa650f/numpy-1.18.1-cp37-cp37m-win_amd64.whl
Collecting Pillow
  Using cached https://files.pythonhosted.org/packages/88/6b/66f502b5ea615f69433ae1e23ec786b2cdadbe41a5cfb1e1fabb4f9c6ce9/Pillow-7.0.0-cp37-cp37m-win_amd64.whl
Collecting pygame
  Using cached https://files.pythonhosted.org/packages/ed/56/b63ab3724acff69f4080e54c4bc5f55d1fbdeeb19b92b70acf45e88a5908/pygame-1.9.6-cp37-cp37m-win_amd64.whl
Installing collected packages: numpy, Pillow, pygame
Successfully installed Pillow-7.0.0 numpy-1.18.1 pygame-1.9.6
Here, we have used the syntax:

pip install -r <file_name>
However, the additional argument -r tells pip that we are passing a requirements file rather than a package name.

Creating Requirements File
You can also use pip freeze command to create your requirements file. Let's look at how to use this command.

Suppose your current Python environment has the following packages. It can be displayed using pip list.

Package    Version
---------- -------
numpy      1.17.0
Pillow     6.1.0
pip        19.3.1
pygame     1.9.6
setuptools 45.0.0
wheel      0.33.6
The packages in your environment that don't come preinstalled will Python are listed using the freeze command.

pip freeze
Output

numpy==1.17.0
Pillow==6.1.0
pygame==1.9.6
The pip freeze command displays the packages and their version in the format of the requirements file.

So this output can be redirected to create a requirements file using the following command:

pip freeze > requirements.txt
A new requirements.txt file is created in the working directory. It can later be used in other Python environments to install specific versions of packages.

To learn more about pip, visit: Python pip (official documentation)