如何在 pandas 中格式化日期格式

Question

I use python and pandas to get yahoo stock market date and save to a local csv file.

DailyPrice = pd.read_csv(file, index_col=0)
print(DailyPrice.tail())

Date
2020-05-27           86.480003  84.370003  86.300003  86.180000  1917600.0 
2020-05-28           87.849998  86.059998  86.870003  86.690002  1908700.0

then I update the date.

History = pdr.DataReader(ticker, start=Before_yesterday, end=Today, data_source='yahoo')
print(History.tail())

Date
2020-06-29  87.360001  86.110001  86.559998  87.290001  1302500.0  87.290001
2020-06-30  88.379997  87.235001  87.330002  88.269997   236377.0  88.269997

then I append date

DailyPrice = DailyPrice.append(History)
print(DailyPrice.tail())

Date
2020-05-27           86.480003  84.370003  86.300003  86.180000  1917600.0 
2020-05-28           87.849998  86.059998  86.870003  86.690002  1908700.0
2020-06-29 00:00:00  87.360001  86.110001  86.559998  87.290001  1302500.0
2020-06-30 00:00:00  88.379997  87.235001  87.330002  88.269997   236377.0

so, my question is: how coul I format the column Date just like %Y-%m-%d, without time hh:mm:ss?

Answer 1

I guess it is the same question as this one

df['Date'] = df['Date'].dt.date

It should work

Answer 2

Looks like you have a DatetimeIndex , you could try to use strftime

DailyPrice.index = DailyPrice.index.strftime('%Y-%m-%d')

Answer 3

I think I find the problem.

Date is not a name of column.

DailyPrice.columns.values.tolist()
['High', 'Low', 'Open', 'Close', 'Volume', 'Adj Close']

so, the first column, Date, what's it?

Date is the index.

at last, issue is resolved.

DailyPrice.index = pd.to_datetime(DailyPrice.index, format = '%Y-%m-%d')