1.. highlightlang:: none 2 3.. _installing-index: 4 5***************************** 6 Installing Python Modules 7***************************** 8 9:Email: distutils-sig@python.org 10 11As a popular open source development project, Python has an active 12supporting community of contributors and users that also make their software 13available for other Python developers to use under open source license terms. 14 15This allows Python users to share and collaborate effectively, benefiting 16from the solutions others have already created to common (and sometimes 17even rare!) problems, as well as potentially contributing their own 18solutions to the common pool. 19 20This guide covers the installation part of the process. For a guide to 21creating and sharing your own Python projects, refer to the 22:ref:`distribution guide <distributing-index>`. 23 24.. note:: 25 26 For corporate and other institutional users, be aware that many 27 organisations have their own policies around using and contributing to 28 open source software. Please take such policies into account when making 29 use of the distribution and installation tools provided with Python. 30 31 32Key terms 33========= 34 35* ``pip`` is the preferred installer program. Starting with Python 2.7.9, it 36 is included by default with the Python binary installers. 37* a virtual environment is a semi-isolated Python environment that allows 38 packages to be installed for use by a particular application, rather than 39 being installed system wide 40* ``virtualenv`` is a third party tools for creating virtual environments, it 41 is defaults to installing ``pip`` into all created virtual environments. 42* the `Python Packaging Index <https://pypi.python.org/pypi>`__ is a public 43 repository of open source licensed packages made available for use by 44 other Python users 45* the `Python Packaging Authority 46 <https://www.pypa.io/en/latest/>`__ are the group of 47 developers and documentation authors responsible for the maintenance and 48 evolution of the standard packaging tools and the associated metadata and 49 file format standards. They maintain a variety of tools, documentation 50 and issue trackers on both `GitHub <https://github.com/pypa>`__ and 51 `BitBucket <https://bitbucket.org/pypa/>`__. 52* ``distutils`` is the original build and distribution system first added to 53 the Python standard library in 1998. While direct use of ``distutils`` is 54 being phased out, it still laid the foundation for the current packaging 55 and distribution infrastructure, and it not only remains part of the 56 standard library, but its name lives on in other ways (such as the name 57 of the mailing list used to coordinate Python packaging standards 58 development). 59 60 61Basic usage 62=========== 63 64The standard packaging tools are all designed to be used from the command 65line. 66 67The following command will install the latest version of a module and its 68dependencies from the Python Packaging Index:: 69 70 python -m pip install SomePackage 71 72.. note:: 73 74 For POSIX users (including Mac OS X and Linux users), the examples in 75 this guide assume the use of a :term:`virtual environment`. You may install 76 ``virtualenv`` to provide such environments using either pip 77 (``pip install virtualenv``) or through your system package manager 78 (commonly called ``virtualenv`` or ``python-virtualenv``). 79 80 For Windows users, the examples in this guide assume that the option to 81 adjust the system PATH environment variable was selected when installing 82 Python. 83 84It's also possible to specify an exact or minimum version directly on the 85command line. When using comparator operators such as ``>``, ``<`` or some other 86special character which get interpreted by shell, the package name and the 87version should be enclosed within double quotes:: 88 89 python -m pip install SomePackage==1.0.4 # specific version 90 python -m pip install "SomePackage>=1.0.4" # minimum version 91 92Normally, if a suitable module is already installed, attempting to install 93it again will have no effect. Upgrading existing modules must be requested 94explicitly:: 95 96 python -m pip install --upgrade SomePackage 97 98More information and resources regarding ``pip`` and its capabilities can be 99found in the `Python Packaging User Guide <https://packaging.python.org>`__. 100 101.. seealso:: 102 103 `Python Packaging User Guide: Installing Python Distribution Packages 104 <https://packaging.python.org/en/latest/installing/>`__ 105 106 107How do I ...? 108============= 109 110These are quick answers or links for some common tasks. 111 112... install ``pip`` in versions of Python prior to Python 2.7.9? 113---------------------------------------------------------------- 114 115Python only started bundling ``pip`` with Python 2.7.9. For earlier versions, 116``pip`` needs to be "bootstrapped" as described in the Python Packaging 117User Guide. 118 119.. seealso:: 120 121 `Python Packaging User Guide: Requirements for Installing Packages 122 <https://packaging.python.org/en/latest/installing/#requirements-for-installing-packages>`__ 123 124 125.. installing-per-user-installation: 126 127... install packages just for the current user? 128----------------------------------------------- 129 130Passing the ``--user`` option to ``python -m pip install`` will install a 131package just for the current user, rather than for all users of the system. 132 133 134... install scientific Python packages? 135--------------------------------------- 136 137A number of scientific Python packages have complex binary dependencies, and 138aren't currently easy to install using ``pip`` directly. At this point in 139time, it will often be easier for users to install these packages by 140`other means 141<https://packaging.python.org/en/latest/science/>`__ 142rather than attempting to install them with ``pip``. 143 144.. seealso:: 145 146 `Python Packaging User Guide: Installing Scientific Packages 147 <https://packaging.python.org/en/latest/science/>`__ 148 149 150... work with multiple versions of Python installed in parallel? 151---------------------------------------------------------------- 152 153On Linux, Mac OS X and other POSIX systems, use the versioned Python commands 154in combination with the ``-m`` switch to run the appropriate copy of 155``pip``:: 156 157 python2 -m pip install SomePackage # default Python 2 158 python2.7 -m pip install SomePackage # specifically Python 2.7 159 python3 -m pip install SomePackage # default Python 3 160 python3.4 -m pip install SomePackage # specifically Python 3.4 161 162(appropriately versioned ``pip`` commands may also be available) 163 164On Windows, use the ``py`` Python launcher in combination with the ``-m`` 165switch:: 166 167 py -2 -m pip install SomePackage # default Python 2 168 py -2.7 -m pip install SomePackage # specifically Python 2.7 169 py -3 -m pip install SomePackage # default Python 3 170 py -3.4 -m pip install SomePackage # specifically Python 3.4 171 172.. other questions: 173 174 Once the Development & Deployment part of PPUG is fleshed out, some of 175 those sections should be linked from new questions here (most notably, 176 we should have a question about avoiding depending on PyPI that links to 177 https://packaging.python.org/en/latest/mirrors/) 178 179 180Common installation issues 181========================== 182 183Installing into the system Python on Linux 184------------------------------------------ 185 186On Linux systems, a Python installation will typically be included as part 187of the distribution. Installing into this Python installation requires 188root access to the system, and may interfere with the operation of the 189system package manager and other components of the system if a component 190is unexpectedly upgraded using ``pip``. 191 192On such systems, it is often better to use a virtual environment or a 193per-user installation when installing packages with ``pip``. 194 195 196Installing binary extensions 197---------------------------- 198 199Python has typically relied heavily on source based distribution, with end 200users being expected to compile extension modules from source as part of 201the installation process. 202 203With the introduction of support for the binary ``wheel`` format, and the 204ability to publish wheels for at least Windows and Mac OS X through the 205Python Packaging Index, this problem is expected to diminish over time, 206as users are more regularly able to install pre-built extensions rather 207than needing to build them themselves. 208 209Some of the solutions for installing `scientific software 210<https://packaging.python.org/en/latest/science/>`__ 211that is not yet available as pre-built ``wheel`` files may also help with 212obtaining other binary extensions without needing to build them locally. 213 214.. seealso:: 215 216 `Python Packaging User Guide: Binary Extensions 217 <https://packaging.python.org/en/latest/extensions/>`__ 218