How to select data for especific time intervals after using Pandas’ resample function? - dataframe

Question

I used Pandas’ resample function for calculating the sales of a list of proucts every 6 months.
I used the resample function for ‘6M’ and using apply({“column-name”:”sum”}).
Now I’d like to create a table with the sum of the sales for the first six months.
How can I extract the sum of the first 6 months, given that all products have records for more than 3 years, and none of them have the same start date?
Thanks in advance for any suggestions.
Here is an example of the data:
Product Date sales
Product 1 6/30/2017 20
12/31/2017 60
6/30/2018 50
12/31/2018 100
Product 2 1/31/2017 30
7/31/2017 150
1/31/2018 200
7/31/2018 300
1/31/2019 100

Answer 1

While waiting for your data, I worked on this. See if this is something that will be helpful for you.
import pandas as pd
df = pd.DataFrame({'Date':['2018-01-10','2018-02-15','2018-03-18',
'2018-07-10','2018-09-12','2018-10-14',
'2018-11-16','2018-12-20','2019-01-10',
'2019-04-15','2019-06-12','2019-10-18',
'2019-12-02','2020-01-05','2020-02-25',
'2020-03-15','2020-04-11','2020-07-22'],
'Sales':[200,300,100,250,150,350,150,200,250,
200,300,100,250,150,350,150,200,250]})
#first breakdown the data by Yearly Quarters
df['YQtr'] = pd.PeriodIndex(pd.to_datetime(df.Date), freq='Q')
#next create a column to identify Half Yearly - H1 for Jan-Jun & H2 for Jul-Dec
df.loc[df['YQtr'].astype(str).str[-2:].isin(['Q1','Q2']),'HYear'] = df['YQtr'].astype(str).str[:-2]+'H1'
df.loc[df['YQtr'].astype(str).str[-2:].isin(['Q3','Q4']),'HYear'] = df['YQtr'].astype(str).str[:-2]+'H2'
#Do a cummulative sum on Half Year to get sales by H1 & H2 for each year
df['HYear_cumsum'] = df.groupby('HYear')['Sales'].cumsum()
#Now filter out only the rows with the max value. That's the H1 & H2 sales figure
df1 = df[df.groupby('HYear')['HYear_cumsum'].transform('max')== df['HYear_cumsum']]
print (df)
print (df1)
The output of this will be:
Source Data + Half Year cumulative sum:
Date Sales YQtr HYear HYear_cumsum
0 2018-01-10 200 2018Q1 2018H1 200
1 2018-02-15 300 2018Q1 2018H1 500
2 2018-03-18 100 2018Q1 2018H1 600
3 2018-07-10 250 2018Q3 2018H2 250
4 2018-09-12 150 2018Q3 2018H2 400
5 2018-10-14 350 2018Q4 2018H2 750
6 2018-11-16 150 2018Q4 2018H2 900
7 2018-12-20 200 2018Q4 2018H2 1100
8 2019-01-10 250 2019Q1 2019H1 250
9 2019-04-15 200 2019Q2 2019H1 450
10 2019-06-12 300 2019Q2 2019H1 750
11 2019-10-18 100 2019Q4 2019H2 100
12 2019-12-02 250 2019Q4 2019H2 350
13 2020-01-05 150 2020Q1 2020H1 150
14 2020-02-25 350 2020Q1 2020H1 500
15 2020-03-15 150 2020Q1 2020H1 650
16 2020-04-11 200 2020Q2 2020H1 850
17 2020-07-22 250 2020Q3 2020H2 250
The half year cumulative sum for each half year.
Date Sales YQtr HYear HYear_cumsum
2 2018-03-18 100 2018Q1 2018H1 600
7 2018-12-20 200 2018Q4 2018H2 1100
10 2019-06-12 300 2019Q2 2019H1 750
12 2019-12-02 250 2019Q4 2019H2 350
16 2020-04-11 200 2020Q2 2020H1 850
17 2020-07-22 250 2020Q3 2020H2 250
I will look at your sample data and work on it later tonight.