Python date 型別轉 datetime 型別
阿新 • • 發佈:2019-01-27
datetime to date
在 Python 中,通過 datetime 獲取到日誌的 date 型別比較簡單, datetime 提供了 date() 方法
In [1]: from datetime import datetime
In [2]: help(datetime.date)
In [3]: datetime.now()
Out[3]: datetime.datetime(2017, 6, 22, 10, 49, 22, 95457)
In [4]: datetime.now().date()
Out[4]: datetime.date(2017, 6, 22)
datetime date 比較
再看看下面一個例子
# coding:utf-8
# python2.7
# Convert date to datetime in Python
from datetime import datetime
today = datetime.now().date()
todaytime = datetime.now()
print today == todaytime
print today > todaytime
執行之後這樣的
# python datetime_date_comp.py
Traceback (most recent call last):
File "datetime_date_comp.py" , line 8, in <module>
today > todaytime
TypeError: can't compare datetime.datetime to datetime.date
datetime 和 date 不能進行 大小比較, 就有一個把 date 型別轉成 datetime 型別的需求了
date to datetime
下面是幾種方式
from datetime import datetime, date
d = date.today()
print datetime.combine(d, datetime.min.time ())
print datetime.fromordinal(d.toordinal())
print datetime(d.year, d.month, d.day)
print datetime(*d.timetuple()[:-4])
simple test
In [8]: %time datetime(*d.timetuple()[:-4])
CPU times: user 10 µs, sys: 0 ns, total: 10 µs
Wall time: 25 µs
Out[8]: datetime.datetime(2017, 6, 22, 0, 0)
In [9]: %time datetime(d.year, d.month, d.day)
CPU times: user 5 µs, sys: 1 µs, total: 6 µs
Wall time: 16 µs
Out[9]: datetime.datetime(2017, 6, 22, 0, 0)
In [10]: %time datetime.fromordinal(d.toordinal())
CPU times: user 6 µs, sys: 0 ns, total: 6 µs
Wall time: 8.11 µs
Out[10]: datetime.datetime(2017, 6, 22, 0, 0)
In [11]: %time datetime.combine(d, datetime.min.time())
CPU times: user 8 µs, sys: 4 µs, total: 12 µs
Wall time: 11 µs
Out[11]: datetime.datetime(2017, 6, 22, 0, 0)
看起來 datetime(d.year, d.month, d.day)
這種方式更好一些。