我尝试在Visual Studio Code中运行简单的绘图代码，但它似乎不起作用。

import matplotlib.pyplot as plt

x = [1,2,3]
y = [4,5,6]
plt.plot(x,y)
plt.show()

这个不断出现：

Traceback (most recent call last):
  File "c:\Users\sony\PycharmProjects\ip project\plot.py", line 1, in <module>
    import matplotlib.pyplot as plt
  File "C:\Users\sony\AppData\Roaming\Python\Python39\site-packages\matplotlib\__init__.py", line 107, in <module>
    from . import _api, cbook, docstring, rcsetup
  File "C:\Users\sony\AppData\Roaming\Python\Python39\site-packages\matplotlib\rcsetup.py", line 27, in <module>
    from matplotlib.fontconfig_pattern import parse_fontconfig_pattern
  File "C:\Users\sony\AppData\Roaming\Python\Python39\site-packages\matplotlib\fontconfig_pattern.py", line 15, in <module>
    from pyparsing import (Literal, ZeroOrMore, Optional, Regex, StringEnd,
ModuleNotFoundError: No module named 'pyparsing'

我试着安装了pyparsing，结果是：

PS C:\Users\sony\OneDrive\Desktop\VSC Python Projects> pip install pyparsing
Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: pyparsing in c:\program files\python39\lib\site-packages (2.4.7)
WARNING: Error parsing requirements for iniconfig: [Errno 2] No such file or directory: 'c:\\program files\\python39\\lib\\site-packages\\iniconfig-1.1.1.dist-info\\METADATA'

为什么会发生这种情况？