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.
Contents
Requirements for Installing Packages
Ensure you can run Python from the command line
Ensure you can run pip from the command line
Ensure pip, setuptools, and wheel are up to date
Optionally, create a virtual environment
Creating Virtual Environments
Use pip for Installing
Installing from PyPI
Source Distributions vs Wheels
Upgrading packages
Installing to the User Site
Requirements files
Installing from VCS
Installing from other Indexes
Installing from a local src tree
Installing from local archives
Installing from other sources
Installing Prereleases
Installing “Extras”
This section describes the steps to follow before installing other Python packages.
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:
You should get some output like Python 3.6.3
. 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.
Note
If you’re a newcomer and you get an error like this:
>>> python3 --version Traceback (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.
Note
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).
Note
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 -m pip
command with python3 -m pip --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.
Additionally, you’ll need to make sure you have pip available. You can check this by running:
If you installed Python from source, with an installer from python.org, or via Homebrew you should already have pip. If you’re on Linux and installed using your OS package manager, you may have to install pip separately, see Installing pip/setuptools/wheel with Linux Package Managers.
If pip
isn’t already installed, then first try to bootstrap it from the
standard library:
If that still doesn’t allow you to run python -m pip
:
Securely Download get-pip.py 1
Run
python get-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
python get-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:
See section below for details, but here’s the basic venv 3 command to use on a typical Linux system:
This will create a new virtual environment in the tutorial_env
subdirectory,
and configure the current shell to use it as the default python
environment.
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:
Using virtualenv:
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.
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”:
To install a specific version:
To install greater than or equal to one version and less than another:
To install a version that’s “compatible” with a certain version: 4
In this case, this means to install any version “==1.4.*” version that’s also “>=1.4.2”.
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.
Wheels are a pre-built distribution format that provides faster installation compared to Source Distributions (sdist), especially when a project contains compiled extensions.
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.
Upgrade an already installed SomeProject
to the latest from PyPI.
To install packages that are isolated to the
current user, use the --user
flag:
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.
Install a list of requirements specified in a Requirements File.
Install a project from VCS in “editable” mode. For a full breakdown of the syntax, see pip’s section on VCS Support.
Install from an alternate index
Search an additional index during install, in addition to PyPI
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.
You can also install normally from src
Install a particular source archive file.
Install from a local directory containing archives (and don’t check PyPI)
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.
./s3helper --port=7777 python -m pip install --extra-index-url http://localhost:7777 SomeProject
Find pre-release and development versions, in addition to stable versions. By default, pip only finds stable versions.
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:
“Secure” in this context means using a modern browser or a tool like curl that verifies SSL certificates when downloading from https URLs.
Depending on your platform, this may require root or Administrator access. pip is currently considering changing this by making user installs the default behavior.
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.
The compatible release specifier was accepted in PEP 440 and support was released in setuptools v8.0 and pip v6.0
联系客服