pandas.DataFrame.first¶

DataFrame.first(self: ~FrameOrSeries, offset) → ~FrameOrSeries[source]¶

Method to subset initial periods of time series data based on a date offset.

Parameters

offsetstr, DateOffset, dateutil.relativedelta

Returns

subsetsame 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.

pandas.DataFrame.filter pandas.DataFrame.first_valid_index