no module named sklearn.cross_validation

install the scikit-learn

CentOs 7.X

sudo yum -y install gcc gcc-c++ numpy python-devel scipy

pip install --user --install-option="--prefix=" -U scikit-learn

no module named numpy

sudo yum install numpy scipy python-matplotlib ipython python-pandas sympy python-nose

centOS 7.X install ipython

sudo -E easy_install ipython