# import necessary libraries
import pandas as pd
import numpy as np

# create sample series
fruits = pd.Series(['apple', 'banana', 'mango', 'apple',
                      'mango', 'apple', 'apple', 'banana'])
values = pd.Series([1, 2, 3, 4, 5, 6, 7, 8])

# calculate mean of grouped values
grouped_mean = {key: values[fruits == key].mean() 
                for key in np.unique(fruits)}

# print the results
print(pd.Series(grouped_mean))