基本上都一样，如下所示

Traceback (most recent call last):
  File "/home/hadoop/PycharmProjects/wjw/ftdd/ftdd/fdfds2011.py", line 9, in <module>
    import matplotlib.pyplot as plt
  File "/home/hadoop/snap/pycharm-community/venv/lib/python3.5/site-packages/matplotlib/pyplot.py", line 2374, in <module>
    switch_backend(rcParams["backend"])
  File "/home/hadoop/snap/pycharm-community/venv/lib/python3.5/site-packages/matplotlib/pyplot.py", line 207, in switch_backend
    backend_mod = importlib.import_module(backend_name)
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "/home/hadoop/snap/pycharm-community/venv/lib/python3.5/site-packages/matplotlib/backends/backend_tkagg.py", line 1, in <module>
    from . import _backend_tk
  File "/home/hadoop/snap/pycharm-community/venv/lib/python3.5/site-packages/matplotlib/backends/_backend_tk.py", line 5, in <module>
    import tkinter as Tk
  File "/usr/lib/python3.5/tkinter/__init__.py", line 38, in <module>
    raise ImportError(str(msg) + ', please install the python3-tk package')
ImportError: No module named '_tkinter', please install the python3-tk package

提示要安装python3-tk，接下来就是各种惊喜了…

开始以为是python自带的库，需要用pip安装。结果搜了一下，竟然没有！

于是网上看了下，大部分都是如下说

tkinter是一个python的接口类库，用以调用tcl/tk程序，故一般在操作系统层面会有相应的类库安装，而非仅仅依靠pip3来安装相应的python类库，比如, python3-tk。

那就直接在系统里安装 python3-tk

sudo apt-get install python3-tk 

没有成功，提示如下：

The following packages have unmet dependencies:
 gnupg : Breaks: software-properties-common (<= 0.96.24.3) but 0.96.20.7 is to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

网上查了下，说是软件包的依赖问题，要重新安装一下依赖包，输入如下代码：

sudo apt-get install software-properties-common=0.96.24.3

结果没有这个版本的包

E: Version '0.96.24.3' for 'software-properties-common' was not found

网上找了一下，发现有software-properties-common (0.96.24.32.1) ，于是重试了一下：

sudo apt-get install software-properties-common=0.96.24.32.1

结果又出现了新的包依赖问题

The following packages have unmet dependencies:
 software-properties-common : Depends: python3-software-properties (= 0.96.24.32.1) but 0.96.20.7 is to be installed
E: Unable to correct problems, you have held broken packages.

网上的建议主要有两种：

• 第一种建议是用aptitude工具
• 第二种建议是更换软件源

我都试了一下。

先用大家说的aptitude工具试一试：

sudo apt install aptitude
sudo aptitude install python3-tk

结果是这样：

The following NEW packages will be installed:
  blt{a} python3-tk python3.6{a} python3.6-minimal{a} tk8.6-blt2.5{a}
The following packages will be upgraded:
  libpython3-stdlib python3 python3-minimal
3 packages upgraded, 5 newly installed, 0 to remove and 1645 not upgraded.
Need to get 677 kB/2,526 kB of archives. After unpacking 12.5 MB will be used.
The following packages have unmet dependencies:
 onboard : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-systemd : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-reportlab-accel : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-gi-cairo : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-brlapi : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-pil : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 rhythmbox-plugins : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-uno : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-cups : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-renderpm : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-pycurl : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-cryptography : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 hplip : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-cffi-backend : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-markupsafe : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 totem-plugins : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-dbus : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-cairo : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-gi : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-lxml : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-gdbm : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 python3-apt : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
 rhythmbox : Depends: python3 (< 3.6) but 3.6.5-3ubuntu1 is to be installed
The following actions will resolve these dependencies:

     Keep the following packages at their current version:
1)     libpython3-stdlib [3.5.1-3 (now)]
2)     python3 [3.5.1-3 (now)]
3)     python3-minimal [3.5.1-3 (now)]
4)     python3-tk [Not Installed]

问我接不接受，我当然不接受，准备采用第二种方案，结果

Accept this solution? [Y/n/q/?] n
open: 6453; closed: 16494; defer: 28; conflict: 39                                                                                                                                                       oNo solution found within the allotted time.  Try harder? [Y/n] Y
Resolving dependencies...
open: 13428; closed: 34395; defer: 31; conflict: 43                                                                                                                                                      ONo solution found within the allotted time.  Try harder? [Y/n] Y
Resolving dependencies...
open: 20374; closed: 52401; defer: 32; conflict: 44                                                                                                                                                      .No solution found within the allotted time.  Try harder? [Y/n] n

没有第二种方案？？？
还出现了这么多新的包依赖问题，在网上查了一下“The following packages have unmet dependencies”这个问题，看到推荐的方法是用“sudo apt-get -f install”来修复，再试一下，结果如下

hadoop@ubun:~$ sudo apt-get install -f
[sudo] password for hadoop:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  linux-headers-4.15.0-29 linux-headers-4.15.0-29-generic linux-image-4.15.0-29-generic linux-modules-4.15.0-29-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 1633 not upgraded.

再运行一下程序，还是bug，不能解决问题。