python : How to find the count of empty cells in one column based on another column element wise?

Question

df = pd.DataFrame({'user': ['Bob', 'Jane', 'Alice','Jane', 'Alice','Bob', 'Alice'], 
               'income': [40000, np.nan, 42000, 50000, np.nan, np.nan, 30000]})

    user   income
0    Bob  40000.0
1   Jane      NaN
2  Alice  42000.0
3   Jane  50000.0
4  Alice      NaN
5    Bob      NaN
6  Alice  30000.0

我想根据 df 中的“用户”列查找“收入”列中所有空值的计数？我正在尝试这样的事情: len(df[df.venue.isnull().sum()]) 但它不完整。

Answer 1

您可以使用方法value_counts():

df.loc[df['income'].isna(), 'user'].value_counts()

输出:

Jane     1
Bob      1
Alice    1
Name: user, dtype: int64