def filter_cat(self, axis, cat_index, cat_name):
    '''
    Filter the matrix based on their category. cat_index is the index of the category, the first category has index=1.
    '''
    run_filter.filter_cat(self, axis, cat_index, cat_name)
Filter the matrix based on their category. cat_index is the index of the category, the first category has index=1.