Series.dt.is_quarter_start Indicator for whether the date is the first day of a quarter.
| Returns: | 
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See also
quarter
is_quarter_end
This method is available on Series with datetime values under the .dt accessor, and directly on DatetimeIndex.
>>> df = pd.DataFrame({'dates': pd.date_range("2017-03-30",
...                   periods=4)})
>>> df.assign(quarter=df.dates.dt.quarter,
...           is_quarter_start=df.dates.dt.is_quarter_start)
       dates  quarter  is_quarter_start
0 2017-03-30        1             False
1 2017-03-31        1             False
2 2017-04-01        2              True
3 2017-04-02        2             False
 >>> idx = pd.date_range('2017-03-30', periods=4)
>>> idx
DatetimeIndex(['2017-03-30', '2017-03-31', '2017-04-01', '2017-04-02'],
              dtype='datetime64[ns]', freq='D')
 >>> idx.is_quarter_start array([False, False, True, False])
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    https://pandas.pydata.org/pandas-docs/version/0.25.0/reference/api/pandas.Series.dt.is_quarter_start.html