计算时间差

import time
time1 = "2019-08-01 19:32:02"
time2 = "2020-01-02 18:21:31"
struct_time1 = time.strptime(time1, "%Y-%m-%d %H:%M:%S")
struct_time2 = time.strptime(time2, "%Y-%m-%d %H:%M:%S")
ret = time.mktime(struct_time1)
res = time.mktime(struct_time2)
time_dif = res - ret
rel = time.localtime(time_dif)
result = "时间相差为%d年%d月%d日%d时%d分%d秒" % (rel.tm_year-1970, rel.tm_mon-1, rel.tm_mday-1, rel.tm_hour, rel.tm_min, rel.tm_sec)
print(result)