pandas.DataFrame.first — pandas 0.24.2 documentation (original) (raw)

DataFrame. first(offset)[source]

Convenience method for subsetting initial periods of time series data based on a date offset.

Parameters: offset : string, DateOffset, dateutil.relativedelta
Returns: subset : same type as caller
Raises: TypeError If the index is not a DatetimeIndex

See also

last

Select final periods of time series based on a date offset.

at_time

Select values at a particular time of the day.

between_time

Select values between particular times of the day.

Examples

i = pd.date_range('2018-04-09', periods=4, freq='2D') ts = pd.DataFrame({'A': [1,2,3,4]}, index=i) ts A 2018-04-09 1 2018-04-11 2 2018-04-13 3 2018-04-15 4

Get the rows for the first 3 days:

ts.first('3D') A 2018-04-09 1 2018-04-11 2

Notice the data for 3 first calender days were returned, not the first 3 days observed in the dataset, and therefore data for 2018-04-13 was not returned.