Pandas:如何更改列中的某些类型观察？

import pandas as pd

data = {'Name': ['John', 'Emma', 'Mike', 'Sarah'],
        'Age': [25, 28, 22, 30],
        'Height': [175.5, 163.2, 180.1, 155.9],
        'Weight': [68.2, 55.7, 73.4, 61.1]}
df = pd.DataFrame(data)

print(df.dtypes)

Name       object
Age         int64
Height    float64
Weight    float64
dtype: object

df['Age'] = df['Age'].astype(str)

print(df.dtypes)

Name       object
Age        object
Height    float64
Weight    float64
dtype: object