Cannot install Python 2 kernel in Jupyter Notebook

Question

I am trying to use a Python program written for Python 2.7. I am using a Macbook Pro running Catalina. The program is here: https://github.com/geoss/censumander. The program has two Jupyter Notebooks to practice with. I have Anaconda 4.9.2 installed and pip 20.2.4. When I open Jupyter Notebook it defaults to Python 3 and has no kernel option to change to Python 2. I have used the guide here to try to install the Python 2 kernel: https://ipython.readthedocs.io/en/latest/install/kernel_install.html.

When I run

python2 -m pip install ipykernel

I get back

Could not find a version that satisfies the requirement ipykernel (from versions: )

No matching distribution found for ipykernel.

I am pretty new to using Python (typically use R) and am trying to get the hang of stuff like this, so apologies if the answer here is obvious. I've tried the solutions here to no avail: Jupyter notebook with Python 2 and Python3 Kernel

I have also tried the solutions here: Jupyter Notebook - install python 2. The first solution

$ python2 /path/to/jupyter-notebook

is unclear to me as I don't understand to what file path the code points (for jupyter_notebook). (This is likely a consequence of my noobiness.)

The second,

conda create -n ipykernel_py2 python=2 ipykernel
conda activate ipykernel_py2    
python -m ipykernel install --user

triggers the following traceback after the third line:

Traceback (most recent call last):
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/runpy.py", line 163, in _run_module_as_main
    mod_name, _Error)
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/runpy.py", line 111, in _get_module_details
    __import__(mod_name)  # Do not catch exceptions initializing package
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/ipykernel/__init__.py", line 2, in <module>
    from .connect import *
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/ipykernel/connect.py", line 13, in <module>
    from IPython.core.profiledir import ProfileDir
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/IPython/__init__.py", line 49, in <module>
    from .terminal.embed import embed
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/IPython/terminal/embed.py", line 18, in <module>
    from IPython.terminal.interactiveshell import TerminalInteractiveShell
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/IPython/terminal/interactiveshell.py", line 16, in <module>
    from prompt_toolkit.document import Document
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/__init__.py", line 16, in <module>
    from .interface import CommandLineInterface
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/interface.py", line 19, in <module>
    from .application import Application, AbortAction
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/application.py", line 3, in <module>
    from .buffer import Buffer, AcceptAction
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/buffer.py", line 7, in <module>
    from .auto_suggest import AutoSuggest
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/auto_suggest.py", line 13, in <module>
    from .filters import to_cli_filter
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/filters/__init__.py", line 33, in <module>
    from .base import *
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/filters/base.py", line 5, in <module>
    from prompt_toolkit.utils import test_callable_args
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/prompt_toolkit/utils.py", line 9, in <module>
    from wcwidth import wcwidth
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/wcwidth/__init__.py", line 12, in <module>
    from .wcwidth import ZERO_WIDTH  # noqa
  File "/opt/anaconda3/envs/ipykernel_py2/lib/python2.7/site-packages/wcwidth/wcwidth.py", line 79, in <module>
    from backports.functools_lru_cache import lru_cache
ImportError: No module named functools_lru_cache

Thanks, all.

Answer 1

From version 5.0 ipykernel only runs on Python 3.4+ (from version 5.2 — 3.5+). To install ipykernel` for Python 2.7 you need an older version:

python2 -m pip install 'ipykernel<5.0'

For backports.functools-lru-cache install or force-reinstall it:

pip install -U backports.functools-lru-cache

or

pip install --ignore-installed backports.functools-lru-cache