如何将datetime对象格式化为带有毫秒的字符串?
当前回答
from datetime import datetime
from time import clock
t = datetime.utcnow()
print 't == %s %s\n\n' % (t,type(t))
n = 100000
te = clock()
for i in xrange(1):
t_stripped = t.strftime('%Y%m%d%H%M%S%f')
print clock()-te
print t_stripped," t.strftime('%Y%m%d%H%M%S%f')"
print
te = clock()
for i in xrange(1):
t_stripped = str(t).replace('-','').replace(':','').replace('.','').replace(' ','')
print clock()-te
print t_stripped," str(t).replace('-','').replace(':','').replace('.','').replace(' ','')"
print
te = clock()
for i in xrange(n):
t_stripped = str(t).translate(None,' -:.')
print clock()-te
print t_stripped," str(t).translate(None,' -:.')"
print
te = clock()
for i in xrange(n):
s = str(t)
t_stripped = s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]
print clock()-te
print t_stripped," s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:] "
结果
t == 2011-09-28 21:31:45.562000 <type 'datetime.datetime'>
3.33410112179
20110928212155046000 t.strftime('%Y%m%d%H%M%S%f')
1.17067364707
20110928212130453000 str(t).replace('-','').replace(':','').replace('.','').replace(' ','')
0.658806915404
20110928212130453000 str(t).translate(None,' -:.')
0.645189262881
20110928212130453000 s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]
translate()和slicing方法的使用同时运行 Translate()的优点是可以在一行中使用
在第一个的基础上比较时间:
1.000 * t.strftime('%Y%m%d%H% m% S%f') 0.351 * str (t) .replace(‘-’,”).replace(‘:’,”).replace(‘。’,”).replace (' “,”) 0.198 * str(t)。翻译(,):。) 0.194 * s[4] +[7] +[8:10] +年代[11:13]+[十四16]+年代(十七19)+ 年代(20:)
其他回答
from datetime import datetime
from time import clock
t = datetime.utcnow()
print 't == %s %s\n\n' % (t,type(t))
n = 100000
te = clock()
for i in xrange(1):
t_stripped = t.strftime('%Y%m%d%H%M%S%f')
print clock()-te
print t_stripped," t.strftime('%Y%m%d%H%M%S%f')"
print
te = clock()
for i in xrange(1):
t_stripped = str(t).replace('-','').replace(':','').replace('.','').replace(' ','')
print clock()-te
print t_stripped," str(t).replace('-','').replace(':','').replace('.','').replace(' ','')"
print
te = clock()
for i in xrange(n):
t_stripped = str(t).translate(None,' -:.')
print clock()-te
print t_stripped," str(t).translate(None,' -:.')"
print
te = clock()
for i in xrange(n):
s = str(t)
t_stripped = s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]
print clock()-te
print t_stripped," s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:] "
结果
t == 2011-09-28 21:31:45.562000 <type 'datetime.datetime'>
3.33410112179
20110928212155046000 t.strftime('%Y%m%d%H%M%S%f')
1.17067364707
20110928212130453000 str(t).replace('-','').replace(':','').replace('.','').replace(' ','')
0.658806915404
20110928212130453000 str(t).translate(None,' -:.')
0.645189262881
20110928212130453000 s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]
translate()和slicing方法的使用同时运行 Translate()的优点是可以在一行中使用
在第一个的基础上比较时间:
1.000 * t.strftime('%Y%m%d%H% m% S%f') 0.351 * str (t) .replace(‘-’,”).replace(‘:’,”).replace(‘。’,”).replace (' “,”) 0.198 * str(t)。翻译(,):。) 0.194 * s[4] +[7] +[8:10] +年代[11:13]+[十四16]+年代(十七19)+ 年代(20:)
我假设您的意思是您正在寻找比datetime.datetime.strftime()更快的东西,并且实际上是从utc时间戳中剥离非alpha字符。
你的方法稍微快一点,我认为你可以通过切片字符串来加快速度:
>>> import timeit
>>> t=timeit.Timer('datetime.utcnow().strftime("%Y%m%d%H%M%S%f")','''
... from datetime import datetime''')
>>> t.timeit(number=10000000)
116.15451288223267
>>> def replaceutc(s):
... return s\
... .replace('-','') \
... .replace(':','') \
... .replace('.','') \
... .replace(' ','') \
... .strip()
...
>>> t=timeit.Timer('replaceutc(str(datetime.datetime.utcnow()))','''
... from __main__ import replaceutc
... import datetime''')
>>> t.timeit(number=10000000)
77.96774983406067
>>> def sliceutc(s):
... return s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]
...
>>> t=timeit.Timer('sliceutc(str(datetime.utcnow()))','''
... from __main__ import sliceutc
... from datetime import datetime''')
>>> t.timeit(number=10000000)
62.378515005111694
字段宽度格式规范
UNIX date命令允许指定%3将精度降低到3位:
$ date '+%Y-%m-%d %H:%M:%S.%3N'
2022-01-01 00:01:23.456
下面是一个自定义函数,它可以在Python中做到这一点:
from datetime import datetime
def strftime_(fmt: str, dt: datetime) -> str:
tokens = fmt.split("%")
tokens[1:] = [_format_token(dt, x) for x in tokens[1:]]
return "".join(tokens)
def _format_token(dt: datetime, token: str) -> str:
if len(token) == 0:
return ""
if token[0].isnumeric():
width = int(token[0])
s = dt.strftime(f"%{token[1]}")[:width]
return f"{s}{token[2:]}"
return dt.strftime(f"%{token}")
使用示例:
>>> strftime_("%Y-%m-%d %H:%M:%S.%3f", datetime.now())
'2022-01-01 00:01:23.456'
注:%%不支持。
要获得以毫秒为单位的日期字符串,使用[:-3]修剪%f(微秒)的最后三位数字:
>>> from datetime import datetime
>>> datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
'2022-09-24 10:18:32.926'
或者稍短一点:
>>> from datetime import datetime
>>> datetime.utcnow().strftime('%F %T.%f')[:-3]
@Cabbi提出了一个问题,在一些系统上(带有Python 2.7的Windows),微秒格式%f可能会错误地给出“0”,所以简单地修改最后三个字符是不可移植的。这样的系统不遵循文档中指定的行为:
Directive | Meaning | Example |
---|---|---|
%f | Microsecond as a decimal number, zero-padded to 6 digits. | 000000, 000001, …, 999999 |
下面的代码小心地以毫秒为单位格式化时间戳:
>>> from datetime import datetime
>>> (dt, micro) = datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f').split('.')
>>> "%s.%03d" % (dt, int(micro) / 1000)
'2016-02-26 04:37:53.133'
为了得到OP想要的准确输出,我们必须去掉标点符号:
>>> from datetime import datetime
>>> (dt, micro) = datetime.utcnow().strftime('%Y%m%d%H%M%S.%f').split('.')
>>> "%s%03d" % (dt, int(micro) / 1000)
'20160226043839901'
推荐文章
- Numpy Max vs amax vs maximum
- 我应该在.gitignore文件中添加Django迁移文件吗?
- 每n行有熊猫
- 实例属性attribute_name定义在__init__之外
- 如何获取在Python中捕获的异常的名称?
- 第一次出现的值大于现有值的Numpy
- 如何从Python函数中返回两个值?
- 前一个月的Python日期
- Python中方括号括起来的列表和圆括号括起来的列表有什么区别?
- Python日志记录不输出任何东西
- 每n秒运行特定代码
- SQLAlchemy是否有与Django的get_or_create等价的函数?
- 如何将python datetime转换为字符串,具有可读格式的日期?
- 美丽的汤和提取div及其内容的ID
- 在Python中重置生成器对象