In python pandas, how do i merge two dataframes while spreading values in one using weights of another?

Question

import pandas as pd

df1 = pd.DataFrame({\'animal\': {0: \'bird\', 1: \'bird\', 2: \'bird\', 3: \'bird\', 4: \'bird\', 5: \'bird\', 6: \'dog\', 7: \'dog\',