item_dict ={}
df = books_metadata[['book_id', 'title']].sort_values('book_id').reset_index()
for i in range(df.shape[0]):
    item_dict[(df.loc[i,'book_id'])] = df.loc[i,'title']
# dummify categorical features
books_metadata_selected_transformed = pd.get_dummies(books_metadata_selected, columns = ['average_rating', 'is_ebook', 'num_pages',                          'publication_year', 'ratings_count', 'language_code'])
books_metadata_selected_transformed = books_metadata_selected_transformed.sort_values('book_id').reset_index().drop('index', axis=1)
books_metadata_selected_transformed.head(5)
# convert to csr matrix
books_metadata_csr = csr_matrix(books_metadata_selected_transformed.drop('book_id', axis=1).values)