pandas.Series.dt.is_month_start

Series.dt.is_month_start

Indicates whether the date is the first day of the month.

Returns

Series or array

For Series, returns a Series with boolean values. For DatetimeIndex, returns a boolean array.

See also

is_month_start

Return a boolean indicating whether the date is the first day of the month.

is_month_end

Return a boolean indicating whether the date is the last day of the month.

Examples

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

>>> s = pd.Series(pd.date_range("2018-02-27", periods=3))
>>> s
0   2018-02-27
1   2018-02-28
2   2018-03-01
dtype: datetime64[ns]
>>> s.dt.is_month_start
0    False
1    False
2    True
dtype: bool
>>> s.dt.is_month_end
0    False
1    True
2    False
dtype: bool

>>> idx = pd.date_range("2018-02-27", periods=3)
>>> idx.is_month_start
array([False, False, True])
>>> idx.is_month_end
array([False, True, False])