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Top Links: >> 80. Technology >> Internet Technology Summit Program >> 9. AI with Python >> 9.1. The Python Tutorial Introduction >> 9.1.6. Brief Tour of the Standard Library Part II >> 9.1.6.1. Virtual Environments and Packages
Current Topic: 9.1.6.1.2. Installing Python Modules
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Email


distutils-sig@python.org




As a popular open source development project, Python has an active supporting community of contributors and users that also make their software available for other Python developers to use under open source license terms.


This allows Python users to share and collaborate effectively, benefiting from the solutions others have already created to common (and sometimes even rare!) problems, as well as potentially contributing their own solutions to the common pool.


This guide covers the installation part of the process. For a guide to creating and sharing your own Python projects, refer to the distribution guide.



Note


For corporate and other institutional users, be aware that many organisations have their own policies around using and contributing to open source software. Please take such policies into account when making use of the distribution and installation tools provided with Python.




Key terms




Changed in version 3.5: The use of venv is now recommended for creating virtual environments.






Basic usage


The standard packaging tools are all designed to be used from the command line.


The following command will install the latest version of a module and its dependencies from the Python Packaging Index:




python -m pip install SomePackage




Note


For POSIX users (including Mac OS X and Linux users), the examples in this guide assume the use of a virtual environment.


For Windows users, the examples in this guide assume that the option to adjust the system PATH environment variable was selected when installing Python.



It's also possible to specify an exact or minimum version directly on the command line. When using comparator operators such as >, < or some other special character which get interpreted by shell, the package name and the version should be enclosed within double quotes:




python -m pip install SomePackage==1.0.4    # specific version
python -m pip install "SomePackage>=1.0.4" # minimum version



Normally, if a suitable module is already installed, attempting to install it again will have no effect. Upgrading existing modules must be requested explicitly:




python -m pip install --upgrade SomePackage



More information and resources regarding pip and its capabilities can be found 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 shown above.





How do I ??


These are quick answers or links for some common tasks.



? install pip in versions of Python prior to Python 3.4?

Was it clear so far?

Python only started bundling pip with Python 3.4. For earlier versions, pip needs to be ?bootstrapped? as described in the Python Packaging User Guide.





? install packages just for the current user?


Passing the --user option to python -m pip install will install a package 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, and aren?t currently easy to install using pip directly. At this point in time, it will often be easier for users to install these packages by other means rather than attempting to install them with pip.





? work with multiple versions of Python installed in parallel?


On Linux, Mac OS X, and other POSIX systems, use the versioned Python commands in combination with the -m switch to run the appropriate copy of pip:




python2   -m pip install SomePackage  # default Python 2
python2.7 -m pip install SomePackage # specifically Python 2.7
python3 -m pip install SomePackage # default Python 3
python3.4 -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 -m switch:




py -2   -m pip install SomePackage  # default Python 2
py -2.7 -m pip install SomePackage # specifically Python 2.7
py -3 -m pip install SomePackage # default Python 3
py -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 part of the distribution. Installing into this Python installation requires root access to the system, and may interfere with the operation of the system package manager and other components of the system if a component is unexpectedly upgraded using pip.


On such systems, it is often better to use a virtual environment or a per-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 end users being expected to compile extension modules from source as part of the installation process.


With the introduction of support for the binary wheel format, and the ability to publish wheels for at least Windows and Mac OS X through the Python Packaging Index, this problem is expected to diminish over time, as users are more regularly able to install pre-built extensions rather than needing to build them themselves.


Some of the solutions for installing scientific software that are not yet available as pre-built wheel files may also help with obtaining other binary extensions without needing to build them locally.









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python -m pip install SomePackage




Note


For POSIX users (including Mac OS X and Linux users), the examples in this guide assume the use of a virtual environment.


For Windows users, the examples in this guide assume that the option to adjust the system PATH environment variable was selected when installing Python.



It's also possible to specify an exact or minimum version directly on the command line. When using comparator operators such as >, < or some other special character which get interpreted by shell, the package name and the version should be enclosed within double quotes:




python -m pip install SomePackage==1.0.4    # specific version
python -m pip install "SomePackage>=1.0.4" # minimum version



Normally, if a suitable module is already installed, attempting to install it again will have no effect. Upgrading existing modules must be requested explicitly:




python -m pip install --upgrade SomePackage



More information and resources regarding pip and its capabilities can be found 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 shown above.



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?







Was it clear so far?


Python only started bundling pip with Python 3.4. For earlier versions, pip needs to be ?bootstrapped? as described in the Python Packaging User Guide.





? install packages just for the current user?


Passing the --user option to python -m pip install will install a package 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, and aren?t currently easy to install using pip directly. At this point in time, it will often be easier for users to install these packages by other means rather than attempting to install them with pip.





? work with multiple versions of Python installed in parallel?


On Linux, Mac OS X, and other POSIX systems, use the versioned Python commands in combination with the -m switch to run the appropriate copy of pip:




python2   -m pip install SomePackage  # default Python 2
python2.7 -m pip install SomePackage # specifically Python 2.7
python3 -m pip install SomePackage # default Python 3
python3.4 -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 -m switch:




py -2   -m pip install SomePackage  # default Python 2
py -2.7 -m pip install SomePackage # specifically Python 2.7
py -3 -m pip install SomePackage # default Python 3
py -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 part of the distribution. Installing into this Python installation requires root access to the system, and may interfere with the operation of the system package manager and other components of the system if a component is unexpectedly upgraded using pip.


On such systems, it is often better to use a virtual environment or a per-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 end users being expected to compile extension modules from source as part of the installation process.


With the introduction of support for the binary wheel format, and the ability to publish wheels for at least Windows and Mac OS X through the Python Packaging Index, this problem is expected to diminish over time, as users are more regularly able to install pre-built extensions rather than needing to build them themselves.


Some of the solutions for installing scientific software that are not yet available as pre-built wheel files may also help with obtaining other binary extensions without needing to build them locally.










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