To install scikit-learn for python3 under Ubuntu 16.04, I used the following commands:
sudo apt-get install python3-dev python3-setuptools python3-scipy python3-matplotlib python3-numpy python3-pip
To get scikit-learn use pip:
pip3 install --user --install-option="--prefix=" -U scikit-learn
To test, if scikit-learn has been installed successfully, you can open up a python3 interpreter
python3
and try to import a submodule of sklearn:
from sklearn import datasets