python pandas按照行数切分文件

import pandas as pd
import time

startTime = int(round(time.time() * 1000))
print("正在拆分，请等待...")
# 读取excel文件
df = pd.read_excel("医生信息导出20220801.xlsx")

# 获取文件总行数
row_num = len(df)
print(row_num)
# 确定每个小文件要包含的数据量
step = 20000

for start in range(0, row_num, step):
    stop = start + step
    filename = "./old_doctor_{}-{}.xlsx".format(start, stop)
    d = df[start: stop]
    print("Saving file : " + filename + ", data size : " + str(len(d)))
    d.to_excel(filename, index=None)

endTime = int(round(time.time() * 1000))
print(str("执行时间为")+repr(((endTime-startTime)/1000)/60)+str("分"))

print('已完成数据拆分')