Pandas:检查低于各自每日阈值的每小时温度值

import pandas as pd

# 加载温度数据到DataFrame
data = {'日期': ['2022-01-01', '2022-01-01', '2022-01-01', '2022-01-02', '2022-01-02', '2022-01-02'],
        '时间': ['00:00', '01:00', '02:00', '00:00', '01:00', '02:00'],
        '温度': [20, 18, 22, 19, 17, 21]}
df = pd.DataFrame(data)

# 将日期和时间列合并为一个时间列
df['时间'] = pd.to_datetime(df['日期'] + ' ' + df['时间'])

# 设置每日阈值
daily_threshold = {'2022-01-01': 19, '2022-01-02': 20}

# 检查低于每日阈值的每小时温度值
df['低于阈值'] = df.apply(lambda row: row['温度'] < daily_threshold[row['日期']], axis=1)

# 打印结果
print(df)

          日期                  时间  温度   低于阈值
0  2022-01-01 2022-01-01 00:00:00  20  False
1  2022-01-01 2022-01-01 01:00:00  18   True
2  2022-01-01 2022-01-01 02:00:00  22  False
3  2022-01-02 2022-01-02 00:00:00  19  False
4  2022-01-02 2022-01-02 01:00:00  17   True
5  2022-01-02 2022-01-02 02:00:00  21  False