pip install network出错：[Errno 13]权限被拒绝

Question

我安装了python 2.7.8以及以下库：

colormath (2.1.0)
numpy (1.9.1)
Pillow (2.7.0)
pip (6.0.8)
setuptools (12.2)
wheel (0.24.0)

我一直在尝试使用networkx安装pip install networkx，并显示以下内容：

Collecting networkx
  Downloading networkx-1.9.1-py2.py3-none-any.whl (1.2MB)
    100% |################################| 1.2MB 248kB/s 
Collecting decorator>=3.4.0 (from networkx)
  Downloading decorator-3.4.2.tar.gz
Installing collected packages: decorator, networkx
  Running setup.py install for decorator
    error: [Errno 13] Permission denied: '/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/decorator.py'
    Complete output from command /Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -c "import setuptools, tokenize;__file__='/private/var/folders/yg/s23bxwb54hx616wzy9gdp6mw0000gn/T/pip-build-F5QMoF/decorator/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/yg/s23bxwb54hx616wzy9gdp6mw0000gn/T/pip-yHW55Y-record/install-record.txt --single-version-externally-managed --compile:
    running install

    running build

    running build_py

    creating build

    creating build/lib

    copying src/decorator.py -> build/lib

    running install_lib

    copying build/lib/decorator.py -> /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages

    error: [Errno 13] Permission denied: '/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/decorator.py'

    ----------------------------------------
    Command "/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python -c "import setuptools, tokenize;__file__='/private/var/folders/yg/s23bxwb54hx616wzy9gdp6mw0000gn/T/pip-build-F5QMoF/decorator/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/yg/s23bxwb54hx616wzy9gdp6mw0000gn/T/pip-yHW55Y-record/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/var/folders/yg/s23bxwb54hx616wzy9gdp6mw0000gn/T/pip-build-F5QMoF/decorator

我不确定该怎么做。