property DatetimeIndex.is_year_start

Indicate whether the date is the first day of a year.

Series or DatetimeIndex

The same type as the original data with boolean values. Series will have the same name and index. DatetimeIndex will have the same name.

See also


Similar property indicating the last day of the year.


This method is available on Series with datetime values under the .dt accessor, and directly on DatetimeIndex.

>>> dates = pd.Series(pd.date_range("2017-12-30", periods=3))
>>> dates
0   2017-12-30
1   2017-12-31
2   2018-01-01
dtype: datetime64[ns]
>>> dates.dt.is_year_start
0    False
1    False
2    True
dtype: bool
>>> idx = pd.date_range("2017-12-30", periods=3)
>>> idx
DatetimeIndex(['2017-12-30', '2017-12-31', '2018-01-01'],
              dtype='datetime64[ns]', freq='D')
>>> idx.is_year_start
array([False, False,  True])