Sparse matrix handling

sparse.py

# Accessing rows and columns.

for ptr in xrange(len(csc.indptr) - 1):
    strptr = csc.indptr[ptr]
    endptr = csc.indptr[ptr + 1]
    temp = xrange(strptr, endptr)
    if temp:
        for row in temp:
            print ptr, csc.data[row], csc.indices[row]