This section covers the basics of how to install Python
packages
.
It’s important to note that the term “package” in this context is being used to
describe a bundle of software to be installed (i.e. as a synonym for a
distribution
). It does not refer to the kind
of
package
that you import in your Python source code
(i.e. a container of modules). It is common in the Python community to refer to
a
distribution
using the term “package”. Using
the term “distribution” is often not preferred, because it can easily be
confused with a Linux distribution, or another larger software distribution
like Python itself.
Before you go any further, make sure you have Python and that the expected
version is available from your command line. You can check this by running:
python3--version
py --version
You should get some output like Python3.6.3. If you do not have Python,
please install the latest 3.x version from python.org or refer to the
Installing Python section of the Hitchhiker’s Guide to Python.
If you’re a newcomer and you get an error like this:
>>> python3--versionTraceback (most recent call last):
File "<stdin>", line 1, in <module>NameError: name 'python3' is not defined
It’s because this command and other suggested commands in this tutorial
are intended to be run in a shell (also called a terminal or
console). See the Python for Beginners getting started tutorial for
an introduction to using your operating system’s shell and interacting with
Python.
If you’re using an enhanced shell like IPython or the Jupyter
notebook, you can run system commands like those in this tutorial by
prefacing them with a ! character:
In [1]: import sys
!{sys.executable} --version
Python 3.6.3
It’s recommended to write {sys.executable} rather than plain python in
order to ensure that commands are run in the Python installation matching
the currently running notebook (which may not be the same Python
installation that the python command refers to).
Due to the way most Linux distributions are handling the Python 3
migration, Linux users using the system Python without creating a virtual
environment first should replace the python command in this tutorial
with python3 and the python-mpip command with python3-mpip--user. Do not
run any of the commands in this tutorial with sudo: if you get a
permissions error, come back to the section on creating virtual environments,
set one up, and then continue with the tutorial as written.
Run pythonget-pip.py. [2] This will install or upgrade pip.
Additionally, it will install Setuptools and wheel if they’re
not installed already.
Warning
Be cautious if you’re using a Python install that’s managed by your
operating system or another package manager. get-pip.py does not
coordinate with those tools, and may leave your system in an
inconsistent state. You can use pythonget-pip.py--prefix=/usr/local/
to install in /usr/local which is designed for locally-installed
software.
While pip alone is sufficient to install from pre-built binary archives,
up to date copies of the setuptools and wheel projects are useful
to ensure you can also install from source archives:
Python “Virtual Environments” allow Python packages to be installed in an isolated location for a particular application,
rather than being installed globally. If you are looking to safely install
global command line tools,
see Installing stand alone command line tools.
Imagine you have an application that needs version 1 of LibFoo, but another
application requires version 2. How can you use both these applications? If you
install everything into /usr/lib/python3.6/site-packages (or whatever your
platform’s standard location is), it’s easy to end up in a situation where you
unintentionally upgrade an application that shouldn’t be upgraded.
Or more generally, what if you want to install an application and leave it be?
If an application works, any change in its libraries or the versions of those
libraries can break the application.
Also, what if you can’t install packages into the
global site-packages directory? For instance, on a shared host.
In all these cases, virtual environments can help you. They have their own
installation directories and they don’t share libraries with other virtual
environments.
Currently, there are two common tools for creating Python virtual environments:
venv is available by default in Python 3.3 and later, and installs
pip into created virtual environments in Python 3.4 and later
(Python versions prior to 3.12 also installed Setuptools).
virtualenv needs to be installed separately, but supports Python 2.7+
and Python 3.3+, and pip, Setuptools and wheel are
always installed into created virtual environments by default (regardless of
Python version).
For more information, see the venv docs or
the virtualenv docs.
The use of source under Unix shells ensures
that the virtual environment’s variables are set within the current
shell, and not in a subprocess (which then disappears, having no
useful effect).
In both of the above cases, Windows users should not use the
source command, but should rather run the activate
script directly from the command shell like so:
<DIR>\Scripts\activate
Managing multiple virtual environments directly can become tedious, so the
dependency management tutorial introduces a
higher level tool, Pipenv, that automatically manages a separate
virtual environment for each project and application that you work on.
pip is the recommended installer. Below, we’ll cover the most common
usage scenarios. For more detail, see the pip docs,
which includes a complete Reference Guide.
pip can install from either Source Distributions (sdist) or Wheels, but if both are present
on PyPI, pip will prefer a compatible wheel. You can override
pip`s default behavior by e.g. using its –no-binary option.
If pip does not find a wheel to install, it will locally build a wheel
and cache it for future installs, instead of rebuilding the source distribution
in the future.
To install packages that are isolated to the
current user, use the --user flag:
python3-mpipinstall--userSomeProject
py -m pip install --user SomeProject
For more information see the User Installs section
from the pip docs.
Note that the --user flag has no effect when inside a virtual environment
- all installation commands will affect the virtual environment.
If SomeProject defines any command-line scripts or console entry points,
--user will cause them to be installed inside the user base’s binary
directory, which may or may not already be present in your shell’s
PATH. (Starting in version 10, pip displays a warning when
installing any scripts to a directory outside PATH.) If the scripts
are not available in your shell after installation, you’ll need to add the
directory to your PATH:
On Linux and macOS you can find the user base binary directory by running
python-msite--user-base and adding bin to the end. For example,
this will typically print ~/.local (with ~ expanded to the absolute
path to your home directory) so you’ll need to add ~/.local/bin to your
PATH. You can set your PATH permanently by modifying ~/.profile.
On Windows you can find the user base binary directory by running py-msite--user-site and replacing site-packages with Scripts. For
example, this could return
C:\Users\Username\AppData\Roaming\Python36\site-packages so you would
need to set your PATH to include
C:\Users\Username\AppData\Roaming\Python36\Scripts. You can set your user
PATH permanently in the Control Panel. You may need to log out for the
PATH changes to take effect.
Install a project from VCS in “editable” mode. For a full breakdown of the
syntax, see pip’s section on VCS Support.
python3-mpipinstall-eSomeProject@git+https://git.repo/some_pkg.git# from git
python3-mpipinstall-eSomeProject@hg+https://hg.repo/some_pkg# from mercurial
python3-mpipinstall-eSomeProject@svn+svn://svn.repo/some_pkg/trunk/# from svn
python3-mpipinstall-eSomeProject@git+https://git.repo/some_pkg.git@feature# from a branch
py -m pip install -e SomeProject @ git+https://git.repo/some_pkg.git # from git
py -m pip install -e SomeProject @ hg+https://hg.repo/some_pkg # from mercurial
py -m pip install -e SomeProject @ svn+svn://svn.repo/some_pkg/trunk/ # from svn
py -m pip install -e SomeProject @ git+https://git.repo/some_pkg.git@feature # from a branch
Installing from local src in
Development Mode,
i.e. in such a way that the project appears to be installed, but yet is
still editable from the src tree.
To install from other data sources (for example Amazon S3 storage)
you can create a helper application that presents the data
in a format compliant with the simple repository API:,
and use the --extra-index-url flag to direct pip to use that index.
Extras are optional “variants” of a package, which may include
additional dependencies, and thereby enable additional functionality
from the package. If you wish to install an extra for a package which
you know publishes one, you can include it in the pip installation command:
python3-mpipinstall'SomePackage[PDF]'
python3-mpipinstall'SomePackage[PDF]==3.0'
python3-mpipinstall-e'.[PDF]'# editable project in current directory
Beginning with Python 3.4, venv (a stdlib alternative to
virtualenv) will create virtualenv environments with pip
pre-installed, thereby making it an equal alternative to
virtualenv.