title: Dimensionality reduction in text data for KNN
body: <p>I have text data (tweets) classified as positive, neutral and negative. I want to test if KNN will do better for reduced dimensions. I tested KNN with different CountVectorizers (different max_feature) from sklearn, but it doesnt really do anything. Is there a point in applying for example PCA or manifold? If yes, how to apply these to text data?</p>