在pandas数据框中创建一列计数

import pandas as pd

data = {'Name': ['John', 'Mike', 'Sarah', 'John', 'Mike', 'John'],
        'Age': [25, 30, 28, 25, 30, 25]}
df = pd.DataFrame(data)

df['Count'] = df['Name'].value_counts()

import pandas as pd

data = {'Name': ['John', 'Mike', 'Sarah', 'John', 'Mike', 'John'],
        'Age': [25, 30, 28, 25, 30, 25]}
df = pd.DataFrame(data)

df['Count'] = df['Name'].value_counts()

print(df)

   Name  Age  Count
0  John   25      3
1  Mike   30      2
2  Sarah  28      1
3  John   25      3
4  Mike   30      2
5  John   25      3