Calling IPython from a virtualenv

alias ipy="python -c 'import IPython; IPython.terminal.ipapp.launch_new_instance()'"

This is a great way of always being sure that the ipython instance always belongs to the virtualenv's python version.

This works only on ipython >2.0.

Source

1. Activate your virtual environment by using source ~/.virtualenvs/my_venv/bin/activate or by running workon my_venv (Depending on how you've installed the my_venv virtual environment)

2. Install ipython

pip install ipython

3. Now run ipython from my_venv.

If it still loads the system's ipython, then run hash -r in your shell

This will reset the cache of your shell and ensure you don't run another ipython that was already called in this shell session.

The answer given by @SiddharthaRT is good! Following this approach, it is simpler for me just:

python -m IPython

This will use the module IPython through the python bin, ensuring that it refers to the bin from the virtual env.

You can force IPython to use a virtual environment if available by adding file below to ~/.ipython/profile_default/startups:

import os
import sys

if 'VIRTUAL_ENV' in os.environ:
    py_version = sys.version_info[:2] # formatted as X.Y 
    py_infix = os.path.join('lib', ('python%d.%d' % py_version))
    virtual_site = os.path.join(os.environ.get('VIRTUAL_ENV'), py_infix, 'site-packages')
    dist_site = os.path.join('/usr', py_infix, 'dist-packages')

    # OPTIONAL: exclude debian-based system distributions sites
    sys.path = filter(lambda p: not p.startswith(dist_site), sys.path)

    # add virtualenv site
    sys.path.insert(0, virtual_site)

I recommend naming it 00-virtualenv.py so changes will be made as early as possible.

Note: Make sure ipython is installed in the new virtual environment to get this to work.