pandas.DataFrame.first#

DataFrame.first(offset)[source]#

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 canselect the first few rows based on a date offset.

Parameters:

offsetstr, DateOffset or dateutil.relativedelta

The offset length of the data that will be selected. For instance,‘1ME’ will display all the rows having their index within the first month.

Returns:

Series or DataFrame

A subset of the caller.

Raises:

TypeError

If the index is not aDatetimeIndex

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            A2018-04-09  12018-04-11  22018-04-13  32018-04-15  4

Get the rows for the first 3 days:

>>>ts.first('3D')            A2018-04-09  12018-04-11  2

Notice the data for 3 first calendar days were returned, not the first3 days observed in the dataset, and therefore data for 2018-04-13 wasnot returned.