3. datetime库和time库

1. 获取当前时间（datetime.datetime.now()）

import datetime
now = datetime.datetime.now()                    #datetime以毫秒形式存储日期和时间；
print('{}年{}月{}日'.format(now.year, now.month, now.day))          #字符串格式化；

2. 获取时间差

datetime.now() - datetime(2017, 8, 19)

3. 用当前时间生成csv文件

a = datetime.datetime.now()  
year = str(a.year)  
month = str(a.month).rjust(2, '0')  
day = str(a.day).rjust(2, '0')  
hour = str(a.hour).rjust(2, '0')  
minute = str(a.minute).rjust(2, '0')  
time_str = 'winrate_' + year + month + day + hour + minute  
best_df.to_csv('output/{}.csv'.format(time_str))

4. 记录代码运行时间

import time
start = time.time()  
best = main()  
end = time.time()  
print("--------程序运行时间为：{}--------".format(str(end - start)))