Assignment1: KNN
- Install BallTree Library: sudo apt-get install python-sklearn
- list.append(), add new item to the end.
- numpy.arange(), sort
- numpy.reshape(), the same with reshape() in matlab
- numpy.median(numpy.array(outs))????
- defaultDict.get(), https://stackoverflow.com/questions/11041405/why-dict-getkey-instead-of-dictkey
- ballTree.query(X, k == k_in), http://scikit-learn.org/stable/modules/generated/sklearn.neighbors.BallTree.html