Pandas: Accessing data with list of dates and DateTimeIndex

Question

I have a pandas DataFrame with a DateTimeIndex:

                           A          B
2016-04-25 18:50:06   440.967796   201.049600  
2016-04-25 18:50:13   441.054995   200.767034  
2016-04-25 18:50:20   441.142337   200.484475
...
2016-07-27 18:50:06   440.967796   201.049600  
2016-07-27 18:50:13   441.054995   200.767034  
2016-07-27 18:50:20   441.142337   200.484475

I would like to extract all the data of a given date yyyy-mm-dd using a list of dates: ['2016-04-25','2016-04-28',...]

I tried the following:

 df[df.index.isin(['2016-04-25', '2016-04-26'])]

 Empty DataFrame

I would like to retrieve all the data (data of the whole day) of the dates given in this list

jezrael · Accepted Answer · 2017-08-29 17:40:28Z

9

You need remove times first by this solutions:

df = df[df.index.normalize().isin(['2016-04-25', '2016-04-26'])]

df = df[df.index.floor('D').isin(['2016-04-25', '2016-04-26'])]

Another solution is compare DatetimeIndex.date, but necessary use numpy.in1d instead isin:

df = df[np.in1d(df.index.date, pd.to_datetime(['2016-04-25', '2016-04-26']).date)]

Or compare strings created DatetimeIndex.strftime:

df = df[np.in1d(df.index.strftime('%Y-%m-%d'), ['2016-04-25', '2016-04-26'])]

print (df)
                              A           B
2016-04-25 18:50:06  440.967796  201.049600
2016-04-25 18:50:13  441.054995  200.767034
2016-04-25 18:50:20  441.142337  200.484475

edited Aug 29, 2017 at 17:40

answered Aug 29, 2017 at 17:35

jezrael

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2 Comments

user3142067 Over a year ago

Thank you. I have a follow up question. Is it possible to cut off the first n data rows in each individual day, without copying any data? The days have different start/end times and different numbers of data rows

jezrael Over a year ago

Hmmm, try df = df.drop(df.groupby(df.index.date).head(2).index) - it remove first 2 value from each date.

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