一次转换数据框的多个列的类型

import pandas as pd

# 创建一个数据框
data = {'A': [1, 2, 3],
        'B': [4, 5, 6],
        'C': [7, 8, 9]}
df = pd.DataFrame(data)

# 转换列的类型
df['A'] = df['A'].astype('float64')
df['B'] = df['B'].astype('str')
df['C'] = df['C'].astype('int32')

# 显示转换后的数据框
print(df.dtypes)