# pandas.DataFrame.first

`DataFrame.``first`(offset)

  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.

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