Python 如何在不同文件夹中合并两个同名excel文件？

我正试图编写一个代码，将5个同名的excel文件合并到不同的文件夹中，这就是我目前得到的问题。问题是它只读取第一个文件，有人能告诉我如何修复它吗？

@stovfl我想将5个excel文件合并到5个不同的文件夹中，我正在尝试前2个文件，看看它是否能在本次模拟中工作，这是否符合您的要求：

   from collections import defaultdict
from glob import glob
from itertools import chain, groupby
import pandas as pd
from pandas import ExcelWriter
from pathlib import Path
from pprint import pprint, pformat
from textwrap import indent
import os
import os.path
ca_2015= "D:\master concordia\DYD\Ecobee DYD\canada\Canada 2015"
ca_2016= "D:\master concordia\DYD\Ecobee DYD\canada\Canada 2016"
ca_2017= "D:\master concordia\DYD\Ecobee DYD\canada\Canada 2017"
ca_2018= "D:\master concordia\DYD\Ecobee DYD\canada\Canada 2018"
ca_2019= "D:\master concordia\DYD\Ecobee DYD\canada\Canada 2019"
files_2015 = os.listdir(ca_2015)
files_2016 = os.listdir(ca_2016)
files_2017 = os.listdir(ca_2017)
files_2018 = os.listdir(ca_2018)
files_2019 = os.listdir(ca_2019)
df_total= pd.DataFrame()

i=0
for file in files_2017:
    os.chdir("D:\master concordia\DYD\Ecobee DYD\canada\Canada 2017")
    if file in files_2018 and file in files_2019:
        df_file= pd.read_csv(file)
        df_total= pd.concat([df_file], ignore_index=True)
        for f in files_2018:
            os.chdir("D:\master concordia\DYD\Ecobee DYD\canada\Canada 2018")
            if f in files_2017 and f in files_2019:
                df_f= pd.read_csv(f)
                df_total= pd.concat([df_f], ignore_index=True)
                for ffile in files_2019:
                    os.chdir("D:\master concordia\DYD\Ecobee DYD\canada\Canada 2019")
                    if ffile in files_2017 and f in files_2018:
                        df_ffile= pd.read_csv(ffile)
                        df_total= pd.concat([df_ffile], ignore_index=True)
                        df_total.to_csv(("thermostat"+str(i)+".csv"),(output_folder))
                        i +=1