Sparse_dot_topn provides a fast way to performing a sparse matrix multiplication
followed by top-n multiplication result selections. Comparing very large feature vectors and
picking the best matches, in practice often results in performing sparse matrix multiplication
followed by selecting the top-n multiplication results. In this package, we implement a
customized Cython function for this purpose. When comparing our Cythonic approach to doing the
same use with SciPy and NumPy functions, our approach improves the speed by about 40% and
reduces memory consumption.
