Using both Python 2.x and Python 3.x in IPython Notebook
The idea here is to install multiple
ipython kernels. Here are instructions for anaconda. If you are not using anaconda, I recently added instructions using pure virtualenvs.
Anaconda >= 4.1.0
Since version 4.1.0, anaconda includes a special package
nb_conda_kernels that detects conda environments with notebook kernels and automatically registers them. This makes using a new python version as easy as creating new conda environments:
conda create -n py27 python=2.7 ipykernelconda create -n py36 python=3.6 ipykernel
After a restart of jupyter notebook, the new kernels are available over the graphical interface. Please note that new packages have to be explicitly installed into the new environments. The Managing environments section in conda's docs provides further information.
Manually registering kernels
Users who do not want to use
nb_conda_kernels or still use older versions of anaconda can use the following steps to manually register ipython kernels.
conda create -n py27 python=2.7conda activate py27conda install notebook ipykernelipython kernel install --user
conda create -n py36 python=3.6conda activate py36conda install notebook ipykernelipython kernel install --user
After that you should be able to choose between
python3 when creating a new notebook in the interface.
Additionally you can pass the
--display-name options to
ipython kernel install if you want to change the names of your kernels. See
ipython kernel install --help for more informations.
These instructions explain how to install a python2 and python3 kernel in separate virtual environments for non-anaconda users. If you are using anaconda, please find my other answer for a solution directly tailored to anaconda.
I assume that you already have
jupyter notebook installed.
First make sure that you have a
python2 and a
python3 interpreter with
On ubuntu you would install these by:
sudo apt-get install python-dev python3-dev python-pip python3-pip
Next prepare and register the kernel environments
python -m pip install virtualenv --user# configure python2 kernelpython -m virtualenv -p python2 ~/py2_kernelsource ~/py2_kernel/bin/activatepython -m pip install ipykernelipython kernel install --name py2 --userdeactivate# configure python3 kernelpython -m virtualenv -p python3 ~/py3_kernelsource ~/py3_kernel/bin/activatepython -m pip install ipykernelipython kernel install --name py3 --userdeactivate
To make things easier, you may want to add shell aliases for the activation command to your shell config file. Depending on the system and shell you use, this can be e.g.
alias kernel2='source ~/py2_kernel/bin/activate'alias kernel3='source ~/py3_kernel/bin/activate'
After restarting your shell, you can now install new packages after activating the environment you want to use.
kernel2python -m pip install <pkg-name>deactivate
kernel3python -m pip install <pkg-name>deactivate