Select initial periods of time series data based on a date offset.
Deprecated since version 2.1: first()
is deprecated and will be removed in a future version. Please create a mask and filter using .loc instead.
For a DataFrame with a sorted DatetimeIndex, this function can select the first few rows based on a date offset.
The offset length of the data that will be selected. For instance, â1MEâ will display all the rows having their index within the first month.
A subset of the caller.
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 calendar days were returned, not the first 3 days observed in the dataset, and therefore data for 2018-04-13 was not returned.
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