Installing Packages - Python Packaging User Guide (original) (raw)

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 adistribution). 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.

Requirements for Installing Packages

This section describes the steps to follow before installing other Python packages.

Ensure you can run Python from the command line

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 theInstalling 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 "", line 1, in 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.

Ensure you can run pip from the command line

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, seeInstalling pip/setuptools/wheel with Linux Package Managers.

If pip isn’t already installed, then first try to bootstrap it from the standard library:

Unix/macOS

python3 -m ensurepip --default-pip

Windows

py -m ensurepip --default-pip

If that still doesn’t allow you to run python -m pip:

Ensure pip, setuptools, and wheel are up to date

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:

Unix/macOS

python3 -m pip install --upgrade pip setuptools wheel

Windows

py -m pip install --upgrade pip setuptools wheel

Optionally, create a virtual environment

See section below for details, but here’s the basic venv [3] command to use on a typical Linux system:

Unix/macOS

python3 -m venv tutorial_env source tutorial_env/bin/activate

Windows

py -m venv tutorial_env tutorial_env\Scripts\activate

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.

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:

The basic usage is like so:

Using venv:

Unix/macOS

python3 -m venv source /bin/activate

Windows

py -m venv \Scripts\activate

Using virtualenv:

Unix/macOS

python3 -m virtualenv source /bin/activate

Windows

virtualenv \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 thesource command, but should rather run the activatescript directly from the command shell like so:

Managing multiple virtual environments directly can become tedious, so thedependency management tutorial introduces a higher level tool, Pipenv, that automatically manages a separate virtual environment for each project and application that you work on.

Use pip for Installing

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.

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. A full description of the supported specifiers can be found in the Version specifier specification. 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 compatiblewith a certain version: [4]

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”.

Source Distributions vs Wheels

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.

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’sPATH. (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:

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

Windows

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 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 inDevelopment 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

Windows

py -m pip install -e

You can also install normally from src

Unix/macOS

python3 -m pip install

Windows

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 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

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