Installing_sklearn

1) install python3 (numpy has one dependency which needs python3.4 so it is better to install python3)
2) install pip python3:
  sudo apt install python3-pip
3) install sklearn:
  pip3 install -U scikit-learn
4) test on python if it is successfully installed:
python3
from sklearn.cluster import KMeans
if everything is imported successfully then its cool, else it will ask to install python numpy
5) install python numpy

pip install --user numpy scipy matplotlib ipython jupyter pandas sympy nose

after this everything will start working. You can check this by using step 4 again.