好吧，就像我看到的，它就像笛卡尔积，然后像上面提到的那样，对期望的输出进行一些操作。

import pandas as pd

df1 = pd.DataFrame({'Class':['banana', 'apple'], 'comp1':[1, 2], 'comp2':[-5, 4]})
df2 = pd.DataFrame({'Element':['K', 'Mg'], 'comp1':[3, -4], 'comp2':[1, 3]}) 
#merging data
output  = df1.merge(df2, how='cross')

output['comp1'] = output.pop('comp1_x') * output.pop('comp1_y')
output['comp2'] = output.pop('comp2_x') * output.pop('comp2_y')
print(output)

expected = pd.DataFrame({'Class': ['banana', 'banana', 'apple', 'apple'], 'Element': ['K', 'Mg', 'K', 'Mg'], 'comp1':[3, -4, 6, -8], 'comp2':[-5, -15, 4, 12]})
print(expected.equals(output)) # True
'''
    Class Element  comp1  comp2
0  banana       K      3     -5
1  banana      Mg     -4    -15
2   apple       K      6      4
3   apple      Mg     -8     12

'''