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As a popular open source development project, Python has an activesupporting community of contributors and users that also make their softwareavailable for other Python developers to use under open source license terms.
This allows Python users to share and collaborate effectively, benefitingfrom the solutions others have already created to common (and sometimeseven rare!) problems, as well as potentially contributing their ownsolutions to the common pool.
This guide covers the installation part of the process. For a guide tocreating and sharing your own Python projects, refer to thePython packaging user guide.
Note
For corporate and other institutional users, be aware that manyorganisations have their own policies around using and contributing toopen source software. Please take such policies into account when makinguse of the distribution and installation tools provided with Python.
Key terms¶
pipis the preferred installer program. Starting with Python 3.4, itis included by default with the Python binary installers.A virtual environment is a semi-isolated Python environment that allowspackages to be installed for use by a particular application, rather thanbeing installed system wide.
venvis the standard tool for creating virtual environments, and hasbeen part of Python since Python 3.3. Starting with Python 3.4, itdefaults to installingpipinto all created virtual environments.virtualenvis a third party alternative (and predecessor) tovenv. It allows virtual environments to be used on versions ofPython prior to 3.4, which either don’t providevenvat all, oraren’t able to automatically installpipinto created environments.The Python Package Index is a publicrepository of open source licensed packages made available for use byother Python users.
the Python Packaging Authority is the group ofdevelopers and documentation authors responsible for the maintenance andevolution of the standard packaging tools and the associated metadata andfile format standards. They maintain a variety of tools, documentation,and issue trackers on GitHub.
distutilsis the original build and distribution system first added tothe Python standard library in 1998. While direct use ofdistutilsisbeing phased out, it still laid the foundation for the current packagingand distribution infrastructure, and it not only remains part of thestandard library, but its name lives on in other ways (such as the nameof the mailing list used to coordinate Python packaging standardsdevelopment).
Changed in version 3.5: The use of venv is now recommended for creating virtual environments.
See also
Python Packaging User Guide: Creating and using virtual environments
Basic usage¶
The standard packaging tools are all designed to be used from the commandline.
The following command will install the latest version of a module and itsdependencies from the Python Package Index:
python -m pip install SomePackage
Note
For POSIX users (including macOS and Linux users), the examples inthis guide assume the use of a virtual environment.
For Windows users, the examples in this guide assume that the option toadjust the system PATH environment variable was selected when installingPython.
It’s also possible to specify an exact or minimum version directly on thecommand line. When using comparator operators such as >, < or some otherspecial character which get interpreted by shell, the package name and theversion should be enclosed within double quotes:
python -m pip install SomePackage==1.0.4 # specific versionpython -m pip install "SomePackage>=1.0.4" # minimum version
Normally, if a suitable module is already installed, attempting to installit again will have no effect. Upgrading existing modules must be requestedexplicitly:
python -m pip install --upgrade SomePackage
More information and resources regarding pip and its capabilities can befound in the Python Packaging User Guide.
Creation of virtual environments is done through the venv module.Installing packages into an active virtual environment uses the commands shownabove.
See also
Python Packaging User Guide: Installing Python Distribution Packages
How do I …?¶
These are quick answers or links for some common tasks.
… install pip in versions of Python prior to Python 3.4?¶
Python only started bundling pip with Python 3.4. For earlier versions,pip needs to be “bootstrapped” as described in the Python PackagingUser Guide.
See also
Python Packaging User Guide: Requirements for Installing Packages
… install packages just for the current user?¶
Passing the --user option to python -m pip install will install apackage just for the current user, rather than for all users of the system.
… install scientific Python packages?¶
A number of scientific Python packages have complex binary dependencies, andaren’t currently easy to install using pip directly. At this point intime, it will often be easier for users to install these packages byother meansrather than attempting to install them with pip.
See also
Python Packaging User Guide: Installing Scientific Packages
… work with multiple versions of Python installed in parallel?¶
On Linux, macOS, and other POSIX systems, use the versioned Python commandsin combination with the -m switch to run the appropriate copy ofpip:
python2 -m pip install SomePackage # default Python 2python2.7 -m pip install SomePackage # specifically Python 2.7python3 -m pip install SomePackage # default Python 3python3.4 -m pip install SomePackage # specifically Python 3.4
Appropriately versioned pip commands may also be available.
On Windows, use the py Python launcher in combination with the -mswitch:
py -2 -m pip install SomePackage # default Python 2py -2.7 -m pip install SomePackage # specifically Python 2.7py -3 -m pip install SomePackage # default Python 3py -3.4 -m pip install SomePackage # specifically Python 3.4
Common installation issues¶
Installing into the system Python on Linux¶
On Linux systems, a Python installation will typically be included as partof the distribution. Installing into this Python installation requiresroot access to the system, and may interfere with the operation of thesystem package manager and other components of the system if a componentis unexpectedly upgraded using pip.
On such systems, it is often better to use a virtual environment or aper-user installation when installing packages with pip.
Pip not installed¶
It is possible that pip does not get installed by default. One potential fix is:
python -m ensurepip --default-pip
There are also additional resources for installing pip.
Installing binary extensions¶
Python has typically relied heavily on source based distribution, with endusers being expected to compile extension modules from source as part ofthe installation process.
With the introduction of support for the binary wheel format, and theability to publish wheels for at least Windows and macOS through thePython Package Index, this problem is expected to diminish over time,as users are more regularly able to install pre-built extensions ratherthan needing to build them themselves.
Some of the solutions for installing scientific softwarethat are not yet available as pre-built wheel files may also help withobtaining other binary extensions without needing to build them locally.
See also
Python Packaging User Guide: Binary Extensions
