and now, for something completely different…

pip & virtualenv

Alex Maneu !@zouave

@PyBcn 20/03/2014

what is this about?

package management

when you need something someone else has written

some examples

SciPy

lxml requests

django pymongo

jars gems eggs(wheels)

where to find them?

PyPI

pypi.python.org

Python Package Index

pipRecommended tool for

installing uninstalling upgrading

packages from PyPI

pip basic commandspip install [—-upgrade] <package> Installs a Python package or upgrades it to the latest available version. !Examples pip install pymongo=1.2 pip install /some/dir/mypackage.tgz pip install http://someserver/mypackage.zip pip install git+ssh://myserver/myrepo.git@feature#egg=MyPackage !!pip uninstall <package> Deletes an already installed package

pip basic commandspip list [—-outdated] Lists installed packages !!pip search <string> Searches for packages whose description contains the specified string

> pip list --outdated amqp (Current: 1.3.3 Latest: 1.4.4) billiard (Current: 3.3.0.8 Latest: 3.3.0.16) celery (Current: 3.1.5 Latest: 3.1.9) …

Examples > pip search cassandra cqlengine - Cassandra CQL 3 Object Mapper for Python CassandraLauncher - Command line utilities for launching Cassandra clusters in EC2 pycassa - Python client library for Apache Cassandra …

what happens if…?

> pip install pymongo !

(…) error: could not create '/Library/Python/2.7/site-packages/bson': Permission denied

virtualenvTool for creating

Python environments

i s o l a t e d

virtualenv

v1 v2 v3django

lxml +

site packages

numpy=1.8.0 pymongo

requests>=2.2.0

site packages

pyOpenSSL, pip, numpy=1.6.2

creating a virtual envvirtualenv [options] <dest_dir> Create a new virtual environment at the specified path. It will contain a copy of all system-wide packages. !

Useful options —-no-site-packages

Create a new empty virtual environment. —-python=<python path>

Use the specified Python executable.

switching to a virtual env> source <dir>/bin/activate (v1)> !

!

Exiting current virtualenv (v1)> deactivate >

cool stuff with pip + virtualenv

!

pip freeze > requirements.txt Create a description file with the packages and versions installed under the current virtualenv. !

pip install -r requirements.txt Install all packages according to the specification in requirements.txt.

summary• Packages: code someone else has written

(SciPy, Django, lxml, pymongo)

• Find packages on PyPI: pypi.python.org

• Install them using pip

• Keep your environment clean by using virtualenv

Thank you!

questions?