PIP Installation doesn't work (six, numpy and python-dateutil requirements)

Question

I'm a quite new to Python and want to install the Pillow package on Mac for Python 3.5. I use the pip install pillowcommand and get this error:

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

So I go on and try to install all the things pandas, html5lib and so on seem to require with pip install six, pip install numpy and pip install python-dateutil and get the next error (for all commands the same):

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.

So I thought all right six and the others are already there and I will just have to upgrade them with the pip install --upgrade six command. And this is were I get the last error and don't now how to continue:

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$ 

So here I'm stuck and would be happy if some of you has a solution to my problem :-)

Answer 1

Just do pip install --ignore-installed pillow, should solve your problem.

Answer 2

For macOS, just try pip install --upgrade --user six. Good luck!