[[ [ ]we will be using numpy lot in this bookand we will refer to objects of the numpy ndarray class as "numpy arraysor just "arrays scipy scipy is collection of functions for scientific computing in python it providesamong other functionalityadvanced linear algebra routinesmathematical function optimizationsignal processingspecial mathematical functionsand statistical distributions scikit-learn draws from scipy' collection of functions for implementing its algorithms the most important part of scipy for us is scipy sparsethis provides sparse matriceswhich are another representation that is used for data in scikitlearn sparse matrices are used whenever we want to store array that contains mostly zerosin[ ]from scipy import sparse create numpy array with diagonal of onesand zeros everywhere else eye np eye( print("numpy array:\ {}format(eye)out[ ]numpy array[ ]in[ ]convert the numpy array to scipy sparse matrix in csr format only the nonzero entries are stored sparse_matrix sparse csr_matrix(eyeprint("\nscipy sparse csr matrix:\ {}format(sparse_matrix)out[ ]scipy sparse csr matrix( ( ( ( introduction