如何在Pandas DataFrame中合并日期时间列并转换为datetime对象

需要将DataFrame中的date列和time列合并为datetime对象，该DataFrame从剪贴板导入，所有字段初始为字符串格式，运行代码后出现报错。

初始数据 #

new_data
Out[90]: 
       date      time  price  price2  price3  price4  var  volume
0  29/09/21  05:07:07      1       1       1       1    1       1
1  01/10/21  06:03:07      1       1       1       1    1       1

执行的代码 #

1. 拼接date和time列

new_data.time=(new_data.date+';'+new_data.time)

拼接后的数据：

new_data
Out[92]: 
       date               time  price  price2  price3  price4  var  volume
0  29/09/21  29/09/21;05:07:07      1       1       1       1    1       1
1  01/10/21  01/10/21;06:03:07      1       1       1       1    1       1

2. 转换为datetime对象

pandas.to_datetime(new_data.time, format='%d/%m/%Y;%H:%M:%S')

报错信息 #

Traceback (most recent call last):

  File "C:\Users\PC1\anaconda3\envs\tf\lib\site-packages\pandas\core\tools\datetimes.py", line 456, in _convert_listlike_datetimes
    values, tz = conversion.datetime_to_datetime64(arg)

  File "pandas\_libs\tslibs\conversion.pyx", line 350, in pandas._libs.tslibs.conversion.datetime_to_datetime64

TypeError: Unrecognized value type: <class 'str'>


During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "<ipython-input-93-74451701a415>", line 1, in <module>
    pandas.to_datetime(new_data.time, format='%d/%m/%Y;%H:%M:%S')

  File "C:\Users\PC1\anaconda3\envs\tf\lib\site-packages\pandas\core\tools\datetimes.py", line 805, in to_datetime
    values = convert_listlike(arg._values, format)

  File "C:\Users\PC1\anaconda3\envs\tf\lib\site-packages\pandas\core\tools\datetimes.py", line 460, in _convert_listlike_datetimes
    raise e

  File "C:\Users\PC1\anaconda3\envs\tf\lib\site-packages\pandas\core\tools\datetimes.py", line 424, in _convert_listlike_datetimes
    arg, format, exact=exact, errors=errors

  File "pandas\_libs\tslibs\strptime.pyx", line 144, in pandas._libs.tslibs.strptime.array_strptime

ValueError: time data '29/09/21;05:07:07' does not match format '%d/%m/%Y;%H:%M:%S' (match)

报错的核心原因是日期格式符不匹配：%Y对应的是4位完整年份（例如2021），但你数据中的年份只有2位（例如21），所以无法解析。

将格式字符串中的大写%Y替换为小写%y即可，%y专门用于匹配2位长度的年份，修正后的代码如下：

pandas.to_datetime(new_data.time, format='%d/%m/%y;%H:%M:%S')

内容的提问来源于stack exchange，提问作者realbro