import pandas as pd
data = [[20200313,0],
        [20200313,1],
        [20200313,2],
        [20200313,0],
        [20200314,0],
        [20200314,1],
        [20200314,2],
        [20200314,1],
        [20200315,0],
        [20200315,1],
        [20200315,2],
        [20200315,2]]

df = pd.DataFrame(data, columns=['date', 'num'])
df['count'] = 1
g = df.groupby(['date', 'num'])['count'].count()

result = g.unstack()

看你这个，并没有解答出我的问题，不过我有了新的思路