问Matplotlib即使所有必需的包都已安装，也不会安装

EN

pip3 install matplotlib==3.0.3
Collecting matplotlib==3.0.3
Using cached matplotlib-3.0.3.tar.gz (36.6 MB)
ERROR: Command errored out with exit status 1:
 command: /Library/Frameworks/Python.framework/Versions/3.8/bin/python3.8 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/var/folders/g5/20g6q1l91sd1v97fz778n5wr0000gp/T/pip-install-yozx599p/matplotlib/setup.py'"'"'; __file__='"'"'/private/var/folders/g5/20g6q1l91sd1v97fz778n5wr0000gp/T/pip-install-yozx599p/matplotlib/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /private/var/folders/g5/20g6q1l91sd1v97fz778n5wr0000gp/T/pip-install-yozx599p/matplotlib/pip-egg-info
     cwd: /private/var/folders/g5/20g6q1l91sd1v97fz778n5wr0000gp/T/pip-install-yozx599p/matplotlib/
Complete output (44 lines):
IMPORTANT WARNING:
    pkg-config is not installed.
    matplotlib may not be able to find some of its dependencies
============================================================================
Edit setup.cfg to change the build options

BUILDING MATPLOTLIB
            matplotlib: yes [3.0.3]
                python: yes [3.8.0 (v3.8.0:fa919fdf25, Oct 14 2019,
                        10:23:27)  [Clang 6.0 (clang-600.0.57)]]
              platform: yes [darwin]

REQUIRED DEPENDENCIES AND EXTENSIONS
                 numpy: yes [version 1.16.2]
      install_requires: yes [handled by setuptools]
                libagg: yes [pkg-config information for 'libagg' could not
                        be found. Using local copy.]
              freetype: no  [The C/C++ header for freetype2 (ft2build.h)
                        could not be found.  You may need to install the
                        development package.]
                   png: yes [pkg-config information for 'libpng' could not
                        be found. Using unknown version found on system.]
                 qhull: yes [pkg-config information for 'libqhull' could not
                        be found. Using local copy.]

OPTIONAL SUBPACKAGES
           sample_data: yes [installing]
              toolkits: yes [installing]
                 tests: no  [skipping due to configuration]
        toolkits_tests: no  [skipping due to configuration]

OPTIONAL BACKEND EXTENSIONS
                   agg: yes [installing]
                 tkagg: yes [installing; run-time loading from Python Tcl /
                        Tk]
                macosx: yes [installing, darwin]
             windowing: no  [Microsoft Windows only]

OPTIONAL PACKAGE DATA
                  dlls: no  [skipping due to configuration]

============================================================================
                        * The following required packages can not be built:
                        * freetype
----------------------------------------