无法在 Jupyter Notebook 中安装 Python 2 内核答案

【问题标题】：Cannot install Python 2 kernel in Jupyter Notebook无法在 Jupyter Notebook 中安装 Python 2 内核
【发布时间】：2021-02-26 11:00:24
【问题描述】：

我正在尝试使用为 Python 2.7 编写的 Python 程序。我正在使用运行 Catalina 的 Macbook Pro。程序在这里：https://github.com/geoss/censumander。该程序有两个 Jupyter Notebooks 可供练习。我安装了 Anaconda 4.9.2 和 pip 20.2.4。当我打开 Jupyter Notebook 时，它默认为 Python 3，并且没有内核选项可以更改为 Python 2。我已使用此处的指南尝试安装 Python 2 内核：https://ipython.readthedocs.io/en/latest/install/kernel_install.html。

当我跑步时

python2 -m pip install ipykernel

我回来了

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

No matching distribution found for ipykernel.

我对使用 Python（通常使用 R）非常陌生，并且正在尝试掌握这样的东西，所以如果这里的答案很明显，我深表歉意。我试过这里的解决方案无济于事：Jupyter notebook with Python 2 and Python3 Kernel

我也尝试过这里的解决方案：Jupyter Notebook - install python 2。第一种解决方案

$ python2 /path/to/jupyter-notebook

我不清楚，因为我不明白代码指向的文件路径（对于 jupyter_notebook）。（这可能是我的菜鸟的结果。）

第二个，

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

在第三行之后触发以下回溯：

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

谢谢大家。

【问题讨论】：

标签： python pip jupyter-notebook kernel

【解决方案1】：

从 5.0 版开始，ipykernel 只能在 Python 3.4+ 上运行（从 5.2 版到 3.5+ 版）。要为 Python 2.7 安装 ipykernel`，您需要旧版本：

python2 -m pip install 'ipykernel<5.0'

对于 backports.functools-lru-cache 安装或强制重新安装：

pip install -U backports.functools-lru-cache

或

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

【讨论】：

感谢您的回复。第一个命令给出：Could not find a version that satisfies the requirement ipykernel<5.0 (from versions: ) No matching distribution found for ipykernel<5.0 你能澄清一下backports.functools 的作用吗？
pip install 'ipykernel==' 并查看可用的版本。对我来说，名单是4.0.1, 4.0.2, 4.0.3, 4.1.0, 4.1.1, 4.2.0, 4.2.1, 4.2.2, 4.3.0, 4.3.1, 4.4.0, 4.4.1, 4.5.0, 4.5.1, 4.5.2, 4.6.0, 4.6.1, 4.7.0, 4.8.0, 4.8.1, 4.8.2, 4.9.0, 4.10.0, 4.10.1
pypi.org/project/backports.functools-lru-cache
ERROR: Could not find a version that satisfies the requirement ipykernel== (from versions: 4.0.1, 4.0.2, 4.0.3, 4.1.0, 4.1.1, 4.2.0, 4.2.1, 4.2.2, 4.3.0, 4.3.1, 4.4.0, 4.4.1, 4.5.0, 4.5.1, 4.5.2, 4.6.0, 4.6.1, 4.7.0, 4.8.0, 4.8.1, 4.8.2, 4.9.0, 4.10.0, 4.10.1, 5.0.0b1, 5.0.0, 5.1.0, 5.1.1, 5.1.2, 5.1.3, 5.1.4, 5.2.0, 5.2.1, 5.3.0, 5.3.1, 5.3.2, 5.3.3, 5.3.4) ERROR: No matching distribution found for ipykernel==
我看到版本 5+，所以您的 pip 不是来自 Python 2.7。试试python2 -m pip install 'ipykernel=='