python3 and opencv on a mac

 brew tap homebrew/science
 brew install opencv3 --with-contrib --with-python3

If you need to use this in a pthon library yyou need to do something like this

    mkdir -p /Users/timothyhseed/Library/Python/2.7/lib/python/site-packages
    echo 'import site; site.addsitedir("/usr/local/lib/python2.7/site-packages")' 

However we want to see the opencv library

cd /usr/local/Cellar/opencv/3.4.0
cd lib
ls

I see python3.6 and 2.7

#Add to Venv

 pe36
 cd ~/pe36/lib/python3-6/site-packages
  ln -s  /usr/local/Cellar/opencv/3.4.0/lib/python3.6/site-packages/cv2.cpython-36m-darwin.so  cv2.so

To test

import cv2  

print(cv2.__version__)