我在Ubuntu 20.04桌面上。我不记得我是否必须在这里手动安装python3pip（必须在其他Ubuntu机器上安装），但我有一个系统：
$ apt-show-versions -r python3-pip
python3-pip:all/focal-updates 20.0.2-5ubuntu1.6 uptodate
...然后:
sudo -H pip3 install --upgrade pip
sudo -H pip3 install pip-tools pipdeptree
sudo -H pip3 install virtualenv
然后，尝试从我的主目录设置virtualenv:
virtualenv venv_mpl
然后，我将以下内容放在venv_mpl/requirements.in中：
plotly
seaborn
scikit-learn
然后，我启用 virtualenv，并尝试安装软件包：
$ source venv_mpl/bin/activate
(venv_mpl) $ pip-compile venv_mpl/requirements.in
...
(venv_mpl) $ pip-sync venv_mpl/requirements.txt
Found existing installation: apturl 0.5.2
ERROR: Cannot uninstall 'apturl'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
Traceback (most recent call last):
...
嗯，是的，我以前确实安装了apturl：
$ apt-show-versions -r apt.*url
apturl:amd64/focal 0.5.2ubuntu19 uptodate
apturl-common:amd64/focal 0.5.2ubuntu19 uptodate
…但话说回来，不应该是这样的吗，如果我使用虚拟环境，那么我就不会有这种问题了？至少，这是我从pip获得的阅读无法卸载
或者，根据您的需要，不使用您的系统Python和/或其全局环境而是创建私有Python安装和/或环境可能会更有效率。这里有许多选项，包括虚拟环境…
那么，我能做些什么，将 pip-compile 从上述 requirements.in 收集的 pip 包安装在如上所述创建的 virtualenv 中？
编辑：如果我尝试删除系统apturl，它还会尝试删除一个关键的桌面组件，在本例中为ubuntu-mate-core：
$ sudo apt remove --dry-run apturl
[sudo] password for administrator:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
apturl ubuntu-mate-core
0 upgraded, 0 newly installed, 2 to remove and 21 not upgraded.
Remv ubuntu-mate-core [1.263]
Remv apturl [0.5.2ubuntu19]
正如@KarlKnechtel所指出的，sudo不应与pip一起使用，所以我尝试这样做-首先，恢复以前的状态（根据OP中所做的更改）：
# answer Y to all questions at next command
sudo -H pip3 uninstall virtualenv pip-tools pipdeptree
rm -rf venv_mpl
现在，由于这目前是Python 3.8.10，我可以使用venv模块，这是3.3以来的标准-但是，我首先需要这样做（错误消息推荐python3.8-venv，但python3-venv可能更好）：
sudo apt install python3-venv
...然后，我可以创建virtualenv:
python3 -m venv venv_mpl
现在，让我们在venv中继续操作，以普通用户的身份运行命令:
$ source venv_mpl/bin/activate
(venv_mpl) $ pip3 install --upgrade pip
...
Successfully installed pip-21.3.1
(venv_mpl) $ pip3 install pip-tools pipdeptree
Collecting pip-tools
...
Successfully installed click-8.0.3 pep517-0.12.0 pip-tools-6.4.0 pipdeptree-2.2.0 tomli-2.0.0 wheel-0.37.0
(venv_mpl) $ cat > venv_mpl/requirements.in <<'EOF'
plotly
seaborn
scikit-learn
EOF
(venv_mpl) $ pip-compile venv_mpl/requirements.in
...
(venv_mpl) $ pip-sync venv_mpl/requirements.txt
Found existing installation: pipdeptree 2.2.0
Uninstalling pipdeptree-2.2.0:
Successfully uninstalled pipdeptree-2.2.0
Collecting cycler==0.11.0
Using cached cycler-0.11.0-py3-none-any.whl (6.4 kB)
Collecting fonttools==4.28.3
Using cached fonttools-4.28.3-py3-none-any.whl (884 kB)
Collecting joblib==1.1.0
Using cached joblib-1.1.0-py2.py3-none-any.whl (306 kB)
Collecting kiwisolver==1.3.2
Using cached kiwisolver-1.3.2-cp38-cp38-manylinux_2_5_x86_64.manylinux1_x86_64.whl (1.2 MB)
Collecting matplotlib==3.5.1
Using cached matplotlib-3.5.1-cp38-cp38-manylinux_2_5_x86_64.manylinux1_x86_64.whl (11.3 MB)
Collecting numpy==1.21.4
Using cached numpy-1.21.4-cp38-cp38-manylinux_2_12_x86_64.manylinux2010_x86_64.whl (15.7 MB)
Collecting packaging==21.3
Using cached packaging-21.3-py3-none-any.whl (40 kB)
Collecting pandas==1.3.5
Using cached pandas-1.3.5-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (11.5 MB)
Collecting pillow==8.4.0
Using cached Pillow-8.4.0-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (3.1 MB)
Collecting plotly==5.4.0
Using cached plotly-5.4.0-py2.py3-none-any.whl (25.3 MB)
Collecting pyparsing==3.0.6
Using cached pyparsing-3.0.6-py3-none-any.whl (97 kB)
Collecting python-dateutil==2.8.2
Using cached python_dateutil-2.8.2-py2.py3-none-any.whl (247 kB)
Collecting pytz==2021.3
Using cached pytz-2021.3-py2.py3-none-any.whl (503 kB)
Collecting scikit-learn==1.0.1
Using cached scikit_learn-1.0.1-cp38-cp38-manylinux_2_12_x86_64.manylinux2010_x86_64.whl (25.9 MB)
Collecting scipy==1.7.3
Using cached scipy-1.7.3-cp38-cp38-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (39.3 MB)
Collecting seaborn==0.11.2
Using cached seaborn-0.11.2-py3-none-any.whl (292 kB)
Collecting six==1.16.0
Using cached six-1.16.0-py2.py3-none-any.whl (11 kB)
Collecting tenacity==8.0.1
Using cached tenacity-8.0.1-py3-none-any.whl (24 kB)
Collecting threadpoolctl==3.0.0
Using cached threadpoolctl-3.0.0-py3-none-any.whl (14 kB)
Installing collected packages: six, pyparsing, pytz, python-dateutil, pillow, packaging, numpy, kiwisolver, fonttools, cycler, threadpoolctl, tenacity, scipy, pandas, matplotlib, joblib, seaborn, scikit-learn, plotly
Successfully installed cycler-0.11.0 fonttools-4.28.3 joblib-1.1.0 kiwisolver-1.3.2 matplotlib-3.5.1 numpy-1.21.4 packaging-21.3 pandas-1.3.5 pillow-8.4.0 plotly-5.4.0 pyparsing-3.0.6 python-dateutil-2.8.2 pytz-2021.3 scikit-learn-1.0.1 scipy-1.7.3 seaborn-0.11.2 six-1.16.0 tenacity-8.0.1 threadpoolctl-3.0.0
好吧，它在这里确实成功了，没有遇到apturl问题——太棒了！
不过，我觉得有点奇怪的是，< code>pipdeptree必须被删除才能成功(编辑:结果是，< code>pipdeptree也必须被添加到< code>requirements.in中，然后它就像所有其他的一样被安装在那里——奇怪的是< code>pip-tools不需要它，然后,< code>pip-tools是解析需求文件的那个；可能相关:请注意，有时“在需求文件中，下列软件包被认为是不安全的:”被打印出来，这里有一些关于不安全软件包背后的原因的讨论...太好了！
EDIT2：如果尝试从这个虚拟环境运行 matplotlib 脚本时，Python 响应“UserWarning：Matplotlib 当前正在使用 agg，这是一个非 GUI 后端，因此无法显示图形”，则需要安装系统 sudo apt install python3-tk（请参阅“用户警告：Matplotlib 当前正在使用 agg，这是一个非 GUI 后端，因此无法显示图形。
