有没有办法使用 jupyter notebook 在同一个 notebook 中运行不同的 python 版本？

Question

I have added the conda environment to my Jupyter notebook, but the Python version is still 3.8 (Fig 1). What I would like to do is to create an environment which contains Python version 3.7 in a Jupyter notebook without starting from a command prompt and running two separate Jupyter notebooks (Fig 2). Is it possible to have simply one jupyter notebook with two separate environments and two different Python versions?

Fig1

Fig2

Answer 1

Please read this page of the docs for ipykernel.

In your environment you want to install only ipykernel (not full Jupyter), and use one of the ipykernel install --name command to register the kernels with Jupyter.

If that does not work, use jupyter kernelspec list to see which kernels jupyter see and where. A kernelspec is at minimum a kernel.json file in the right place to tell jupyter how to find kernels.

For example I have the following

$ cat ~/miniconda3/share/jupyter/kernels/python3/kernel.json
{
 "argv": [
  "~/miniconda3/bin/python",
  "-m",
  "ipykernel_launcher",
  "-f",
  "{connection_file}"
 ],
 "display_name": "Python 3 (ipykernel)",
 "language": "python",
 "metadata": {
  "debugger": true
 }
}

I can use the documentation above, or create the following by hand:

$ cat ~/miniconda3/share/jupyter/kernels/python3.6/kernel.json
{
 "argv": [
  "~/miniconda3/envs/mypython36env/bin/python",
  "-m",
  "ipykernel_launcher",
  "-f",
  "{connection_file}"
 ],
 "display_name": "Python 3.6 !!",
 "language": "python",
 "metadata": {
  "debugger": true
 }
}

and assuming I have the corresponding Python 3.6 env, then I'll get two kernel one of them being Python 3.6