# pandas.DatetimeIndex.is_month_start

`DatetimeIndex.``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])

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