如何在 Pandas 中将数据格式更改为“%Y%m%d”？
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How to change format of data to '%Y%m%d' in Pandas?
提问by Joe
I have a DF with first column showing as e.g. 2018-01-31 00:00:00.
我有一个 DF，第一列显示为例如2018-01-31 00:00:00。
I want to convert whole column (or during printing / saving to other variable) that date to 20180131format.
NOT looking to do that during saving to a CSV file.
我想将该日期的整列（或在打印/保存到其他变量期间）20180131转换为格式。在保存到 CSV 文件期间不希望这样做。
Tried this but it did not work:
试过这个，但没有用：
df['mydate'] = pd.to_datetime(df['mydate'], format='%Y%m%d')
df['mydate'] = pd.to_datetime(df['mydate'], format='%Y%m%d')
回答by jpp
pd.to_datetimeis used to convert your series to datetime:
pd.to_datetime用于将您的系列转换为datetime：
s = pd.Series(['2018-01-31 00:00:00'])
s = pd.to_datetime(s)
print(s)
0 2018-01-31
dtype: datetime64[ns]
pd.Series.dt.strftimeconverts your datetimeseries to a string in your desired format:
pd.Series.dt.strftime将您的datetime系列转换为所需格式的字符串：
s = s.dt.strftime('%Y%m%d')
print(s)
0 20180131
dtype: object
回答by Dan
pd.to_datetimewill convert a string to a date. You want to covert a date to a string
pd.to_datetime将字符串转换为日期。您想将日期转换为字符串
df['mydate'].dt.strftime('%Y%m%d')
Note that it's possible your date is already a string, but in the wrong format in which case you maight have to convert it to a date first:
请注意，您的日期可能已经是一个字符串，但格式错误，在这种情况下，您可能必须先将其转换为日期：
pd.to_datetime(df['mydate'], format='%Y-%m-%d %H:%M:S').dt.strftime('%Y%m%d')
