PIP安装不起作用（六、numpy和python-dateutil要求）

我是 Python 新手，想在 Mac 上安装 Python 3.5 的 Pillow 包。我用pip install pillow命令并收到此错误：

Jaspers-MBP:~ jasperherrmann$ pip install pillow
Collecting pillow
  Using cached Pillow-5.1.0-cp27-cp27m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl
prompt-toolkit 1.0.15 has requirement six>=1.9.0, but you'll have six 
1.4.1 which is incompatible.
pandas 0.22.0 has requirement numpy>=1.9.0, but you'll have numpy 1.8.0rc1 which is incompatible.
html5lib 1.0.1 has requirement six>=1.9, but you'll have six 1.4.1 which is incompatible.
matplotlib 1.3.1 has requirement numpy>=1.5, but you'll have numpy 1.8.0rc1 which is incompatible.
jupyter-client 5.2.3 has requirement python-dateutil>=2.1, but you'll have python-dateutil 1.5 which is incompatible.
Installing collected packages: pillow

所以我继续尝试安装 pandas、html5lib 等似乎需要的所有东西pip install six, pip install numpy and pip install python-dateutil并得到下一个错误（对于所有命令都相同）：

Jaspers-MBP:~ jasperherrmann$ pip install six
Requirement already satisfied: six in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python (1.4.1)
prompt-toolkit 1.0.15 has requirement six>=1.9.0, but you'll have six 1.4.1 which is incompatible.
pandas 0.22.0 has requirement numpy>=1.9.0, but you'll have numpy 1.8.0rc1 which is incompatible.
html5lib 1.0.1 has requirement six>=1.9, but you'll have six 1.4.1 which is incompatible.
matplotlib 1.3.1 has requirement numpy>=1.5, but you'll have numpy 1.8.0rc1 which is incompatible.
jupyter-client 5.2.3 has requirement python-dateutil>=2.1, but you'll have python-dateutil 1.5 which is incompatible.

所以我想好吧，六个和其他已经在那里了，我只需要用pip install --upgrade six命令。这是我收到最后一个错误但现在不知道如何继续：

Jaspers-MBP:~ jasperherrmann$ pip install --upgrade six
Collecting six
  Using cached six-1.11.0-py2.py3-none-any.whl
pandas 0.22.0 has requirement numpy>=1.9.0, but you'll have numpy 1.8.0rc1 which is incompatible.
matplotlib 1.3.1 has requirement numpy>=1.5, but you'll have numpy 1.8.0rc1 which is incompatible.
jupyter-client 5.2.3 has requirement python-dateutil>=2.1, but you'll have python-dateutil 1.5 which is incompatible.
Installing collected packages: six
  Found existing installation: six 1.4.1
Cannot uninstall 'six'. 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.
Jaspers-MBP:~ jasperherrmann$ 

所以我被困住了，如果你们中的一些人能解决我的问题，我会很高兴:-)

Just do pip install --ignore-installed pillow，应该可以解决你的问题。