Python 在Pandas中,如何将日期字符串转换为datetime对象并将其放入数据帧中?
此代码位产生错误: TypeError:“'int'对象不可编辑” 谁能告诉我如何将这一系列日期时间字符串作为Python 在Pandas中,如何将日期字符串转换为datetime对象并将其放入数据帧中?,python,datetime,pandas,Python,Datetime,Pandas,此代码位产生错误: TypeError:“'int'对象不可编辑” 谁能告诉我如何将这一系列日期时间字符串作为DateTime对象放入数据帧中 import pandas as pd date_stngs = ('2008-12-20','2008-12-21','2008-12-22','2008-12-23') a = pd.Series(range(4),index = (range(4))) for idx, date in enumerate(date_stngs): a[
DateTime
对象放入数据帧中
import pandas as pd
date_stngs = ('2008-12-20','2008-12-21','2008-12-22','2008-12-23')
a = pd.Series(range(4),index = (range(4)))
for idx, date in enumerate(date_stngs):
a[idx]= pd.to_datetime(date)
更新
使用pandas.to_datetime(pd.Series(..)。它比上面的代码简洁且速度快得多
>>> import pandas as pd
>>> date_stngs = ('2008-12-20','2008-12-21','2008-12-22','2008-12-23')
>>> a = pd.Series([pd.to_datetime(date) for date in date_stngs])
>>> a
0 2008-12-20 00:00:00
1 2008-12-21 00:00:00
2 2008-12-22 00:00:00
3 2008-12-23 00:00:00
更新:基准
一个简单的解决方案涉及系列构造函数。只需将数据类型传递给
dtype
参数即可。另外,to_datetime
函数现在可以获取字符串序列
创建数据
In [43]: dates = [(dt.datetime(1960, 1, 1)+dt.timedelta(days=i)).date().isoformat() for i in range(20000)]
In [44]: timeit pd.Series([pd.to_datetime(date) for date in dates])
1 loops, best of 3: 1.71 s per loop
In [45]: timeit pd.to_datetime(pd.Series(dates))
100 loops, best of 3: 5.71 ms per loop
这三种产品都生产相同的产品
基准
@waitingkuo提供的基准是错误的。第一种方法比其他两种性能相同的方法慢一点
pd.Series(date_strings, dtype='datetime64[ns]')
pd.Series(pd.to_datetime(date_strings))
pd.to_datetime(pd.Series(date_strings))
比pd.to_datetime(pd.Series(date_stngs))慢一百倍。强烈不推荐这种方法。@DickEshelman,waitingkuo的版本更优雅。@waitingkuo,我同意你的版本更简洁。但是你的版本比我的快不了100倍
timeit.timeit
我的,你的,显示的差别很小。@waitingkuo,我升级到了0.11.0。你是对的。“我真丢脸!”费米欧波尔塔,我也差不多。(Python 2.7.8,pandas 0.14.1,Windows 7):为什么要对datetime->datetime
转换进行基准测试,而不是str->datetime
?很抱歉,我错过了。对于2017+的答案,请参阅
In [43]: dates = [(dt.datetime(1960, 1, 1)+dt.timedelta(days=i)).date().isoformat() for i in range(20000)]
In [44]: timeit pd.Series([pd.to_datetime(date) for date in dates])
1 loops, best of 3: 1.71 s per loop
In [45]: timeit pd.to_datetime(pd.Series(dates))
100 loops, best of 3: 5.71 ms per loop
date_strings = ('2008-12-20','2008-12-21','2008-12-22','2008-12-23')
pd.Series(date_strings, dtype='datetime64[ns]')
pd.Series(pd.to_datetime(date_strings))
pd.to_datetime(pd.Series(date_strings))
import datetime as dt
dates = [(dt.datetime(1960, 1, 1)+dt.timedelta(days=i)).date().isoformat()
for i in range(20000)] * 100
%timeit pd.Series(dates, dtype='datetime64[ns]')
730 ms ± 9.06 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
%timeit pd.Series(pd.to_datetime(dates))
426 ms ± 3.45 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
%timeit pd.to_datetime(pd.Series(dates))
430 ms ± 5.7 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)