Filter dataframe for past 4 quarters

February 14, 2023

I have a DataFrame with start date and end date as a column. Firstly I need create a new column using End Date which consists of yearquarter (2022Q4) which I did using below code:

df[‘Quarter’]=pd.PeriodIndex(d[‘End Date’],freq=’Q’)

Now I want to filter data for past 4 quarters using End Date, lets say curremtly its 2023Q1, so I want to filter so That I can get data for (2022Q1, 2022Q2, 2022Q3, 2022Q4).

How can I achieve this in python.

>Solution :

Use Serie.dt.to_period for quarters with generate actual quarter by Timestamp and Timestamp.to_period, last filter by boolean indexing with Series.between:

df = pd.DataFrame({'End Date':pd.date_range('2021-12-01', freq='25D', periods=20)})
    
df['Quarter'] = df['End Date'].dt.to_period('q')

now = pd.Timestamp.now().to_period('q')

out = df[df['Quarter'].between(now - 4, now - 1)]
print (out)
     End Date Quarter
2  2022-01-20  2022Q1
3  2022-02-14  2022Q1
4  2022-03-11  2022Q1
5  2022-04-05  2022Q2
6  2022-04-30  2022Q2
7  2022-05-25  2022Q2
8  2022-06-19  2022Q2
9  2022-07-14  2022Q3
10 2022-08-08  2022Q3
11 2022-09-02  2022Q3
12 2022-09-27  2022Q3
13 2022-10-22  2022Q4
14 2022-11-16  2022Q4
15 2022-12-11  2022Q4