anaconda – How to know which Python is running in Jupyter notebook?

from platform import python_version

print(python_version())

This will give you the exact version of python running your script. eg output:

3.6.5

import sys
sys.executable

will give you the interpreter. You can select the interpreter you want when you create a new notebook. Make sure the path to your anaconda interpreter is added to your path (somewhere in your bashrc/bash_profile most likely).

For example I used to have the following line in my .bash_profile, that I added manually :

export PATH=$HOME/anaconda3/bin:$PATH

EDIT: As mentioned in a comment, this is not the proper way to add anaconda to the path. Quoting Anacondas doc, this should be done instead after install, using conda init:

Should I add Anaconda to the macOS or Linux PATH?

We do not recommend adding Anaconda to the PATH manually. During
installation, you will be asked “Do you wish the installer to
initialize Anaconda3 by running conda init?” We recommend “yes”. If
you enter “no”, then conda will not modify your shell scripts at all.
In order to initialize after the installation process is done, first
run source <path to conda>/bin/activate and then run conda init

anaconda – How to know which Python is running in Jupyter notebook?

import sys
print(sys.executable)
print(sys.version)
print(sys.version_info)

Seen below :- output when i run JupyterNotebook outside a CONDA venv

/home/dhankar/anaconda2/bin/python
2.7.12 |Anaconda 4.2.0 (64-bit)| (default, Jul  2 2016, 17:42:40) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
sys.version_info(major=2, minor=7, micro=12, releaselevel=final, serial=0)

Seen below when i run same JupyterNoteBook within a CONDA Venv created with command —

conda create -n py35 python=3.5 ## Here - py35 , is name of my VENV

in my Jupyter Notebook it prints :-

/home/dhankar/anaconda2/envs/py35/bin/python
3.5.2 |Continuum Analytics, Inc.| (default, Jul  2 2016, 17:53:06) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)]
sys.version_info(major=3, minor=5, micro=2, releaselevel=final, serial=0)

also if you already have various VENVs created with different versions of Python you switch to the desired Kernel by choosing KERNEL >> CHANGE KERNEL from within the JupyterNotebook menu…
JupyterNotebookScreencapture

Also to install ipykernel within an existing CONDA Virtual Environment –

http://ipython.readthedocs.io/en/stable/install/kernel_install.html#kernels-for-different-environments

Source — https://github.com/jupyter/notebook/issues/1524

 $ /path/to/python -m  ipykernel install --help
 usage: ipython-kernel-install [-h] [--user] [--name NAME]
                          [--display-name DISPLAY_NAME]
                          [--profile PROFILE] [--prefix PREFIX]
                          [--sys-prefix]

Install the IPython kernel spec.

optional arguments:
-h, –help show this help message and exit
–user Install for the current user instead of system-wide
–name NAME Specify a name for the kernelspec. This is needed to
have multiple IPython kernels at the same time.
–display-name DISPLAY_NAME
Specify the display name for the kernelspec. This is
helpful when you have multiple IPython kernels.
–profile PROFILE Specify an IPython profile to load. This can be used
to create custom versions of the kernel.
–prefix PREFIX Specify an install prefix for the kernelspec. This is
needed to install into a non-default location, such as
a conda/virtual-env.
–sys-prefix Install to Pythons sys.prefix. Shorthand for
–prefix=/Users/bussonniermatthias/anaconda. For use
in conda/virtual-envs.