在pandas中按天、月和时间(不是按年)合并xlsx文件

import pandas as pd
import glob

file_paths = glob.glob('*.xlsx')

merged_data = pd.DataFrame()

for file_path in file_paths:
    data = pd.read_excel(file_path)
    merged_data = pd.concat([merged_data, data])

merged_data['日期'] = pd.to_datetime(merged_data['日期'])

data_by_day = merged_data.groupby(pd.Grouper(key='日期', freq='D')).sum()

data_by_month = merged_data.groupby(pd.Grouper(key='日期', freq='M')).sum()

data_by_time = merged_data.groupby(merged_data['日期'].dt.time).sum()