Installing Packages¶

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 to 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.

Creating Virtual Environments¶

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 and setuptools into created virtual environments in
  Python 3.4 and later.

• 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).

The basic usage is like so:

Using venv:

Unix/macOS

python3 -m venv <DIR>
source
 <DIR>/bin/activate

Windows

py -m venv 
<
DIR>
<
DIR
>
\Scripts\activate

Using virtualenv:

Unix/macOS

python3 -m virtualenv <DIR>
source
 <DIR>/bin/activate

Windows

virtualenv 
<
DIR>
<
DIR
>
\Scripts\activate

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.

Installing from PyPI¶

The most common usage of pip is to install from the Python Package
Index using a requirement specifier. Generally speaking, a requirement specifier is
composed of a project name followed by an optional version specifier. PEP 440 contains a full
specification
of the currently supported specifiers. Below are some examples.

To install the latest version of “SomeProject”:

Unix/macOS

python3 -m pip install 
"SomeProject"

Windows

py -m pip install 
"SomeProject"

To install a specific version:

Unix/macOS

python3 -m pip install 
"SomeProject==1.4"

Windows

py -m pip install 
"SomeProject==1.4"

To install greater than or equal to one version and less than another:

Unix/macOS

python3 -m pip install 
"SomeProject>=1,<2"

Windows

py -m pip install 
"SomeProject>=1,<2"

To install a version that’s “compatible”
with a certain version:

Unix/macOS

python3 -m pip install 
"SomeProject~=1.4.2"

Windows

py -m pip install 
"SomeProject~=1.4.2"

In this case, this means to install any version “==1.4.*” version that’s also
“>=1.4.2”.

Upgrading packages¶

Upgrade an already installed SomeProject to the latest from PyPI.

Unix/macOS

python3 -m pip install --upgrade SomeProject

Windows

py -m pip install --upgrade SomeProject

Installing to the User Site¶

To install packages that are isolated to the
current user, use the --user flag:

Unix/macOS

python3 -m pip install --user SomeProject

Windows

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 -m site --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 -m
site --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.

Requirements files¶

Install a list of requirements specified in a Requirements File.

Unix/macOS

python3 -m pip install -r requirements.txt

Windows

py -m pip install -r requirements.txt

Installing from VCS¶

Install a project from VCS in “editable” mode. For a full breakdown of the
syntax, see pip’s section on VCS Support.

Unix/macOS

python3 -m pip install -e git+https://git.repo/some_pkg.git#egg
=
SomeProject          
# from git
python3 -m pip install -e hg+https://hg.repo/some_pkg#egg
=
SomeProject                
# from mercurial
python3 -m pip install -e svn+svn://svn.repo/some_pkg/trunk/#egg
=
SomeProject         
# from svn
python3 -m pip install -e git+https://git.repo/some_pkg.git@feature#egg
=
SomeProject  
# from a branch

Windows

py -m pip install -e git+https://git.repo/some_pkg.git#egg=SomeProject          # from git
py -m pip install -e hg+https://hg.repo/some_pkg#egg=SomeProject                # from mercurial
py -m pip install -e svn+svn://svn.repo/some_pkg/trunk/#egg=SomeProject         # from svn
py -m pip install -e git+https://git.repo/some_pkg.git@feature#egg=SomeProject  # from a branch

Installing from other Indexes¶

Install from an alternate index

Unix/macOS

python3 -m pip install --index-url http://my.package.repo/simple/ SomeProject

Windows

py -m pip install --index-url http://my.package.repo/simple/ SomeProject

Search an additional index during install, in addition to PyPI

Unix/macOS

python3 -m pip install --extra-index-url http://my.package.repo/simple SomeProject

Windows

py -m pip install --extra-index-url http://my.package.repo/simple SomeProject

Installing from a local src tree¶

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.

Unix/macOS

python3 -m pip install -e <path>

Windows

py -m pip install -e 
<
path>

You can also install normally from src

Unix/macOS

python3 -m pip install <path>

Windows

py -m pip install 
<
path>

Installing from local archives¶

Install a particular source archive file.

Unix/macOS

python3 -m pip install ./downloads/SomeProject-1.0.4.tar.gz

Windows

py -m pip install ./downloads/SomeProject-1.0.4.tar.gz

Install from a local directory containing archives (and don’t check PyPI)

Unix/macOS

python3 -m pip install --no-index --find-links
=
file:///local/dir/ SomeProject
python3 -m pip install --no-index --find-links
=
/local/dir/ SomeProject
python3 -m pip install --no-index --find-links
=
relative/dir/ SomeProject

Windows

py -m pip install --no-index --find-links=file:///local/dir/ SomeProject
py -m pip install --no-index --find-links=/local/dir/ SomeProject
py -m pip install --no-index --find-links=relative/dir/ SomeProject

Installing from other sources¶

To install from other data sources (for example Amazon S3 storage) you can
create a helper application that presents the data in a PEP 503 compliant
index format, and use the --extra-index-url flag to direct pip to use
that index.

./s3helper --port
=
7777
python -m pip install --extra-index-url http://localhost:7777 SomeProject

Installing Prereleases¶

Find pre-release and development versions, in addition to stable versions. By
default, pip only finds stable versions.

Unix/macOS

python3 -m pip install --pre SomeProject

Windows

py -m pip install --pre SomeProject

Installing “Extras”¶

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:

Unix/macOS

python3 -m pip install SomePackage
[
PDF
]
python3 -m pip install SomePackage
[
PDF
]==
3
.0
python3 -m pip install -e .
[
PDF
]
  
# editable project in current directory

Windows

py -m pip install SomePackage[PDF]
py -m pip install SomePackage[PDF]==3.0
py -m pip install -e .[PDF]  # editable project in current directory