定义一个DataFrame

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>>> data = {'state': ['US','Ohio','Nevada'], 'date':['2001-09-12 21:11:09', '2001-09-13 06:32:19', '2002-02-23 04:12:19']}
>>> df = pd.DataFrame(data)
>>> df
date state
0 2001-09-12:21 11:09 US
1 2001-09-13:06 32:19 Ohio
2 2002-02-23:04 12:19 Nevada
>>> df['date']
0 2001-09-12 21:11:09
1 2001-09-13 06:32:19
2 2002-02-23 04:12:19
Name: date, dtype: object

可以看到date列的dtype为object,现在需要转换成日期格式

可以使用to_datetime来转换:

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>>> pd.to_datetime(df['date'])
0 2001-09-12 21:11:09
1 2001-09-13 06:32:19
2 2002-02-23 04:12:19
Name: date, dtype: datetime64[ns]

Pandas已经自动将该列由object转成datetime64[ns]