How To Apply For Loop To Append Rows Based On Multiple Calculation?

I have a very complex situation to append the rows with one agg. function of sum of population based on different columns. Find below: Please make sure I have multiple rows in all

Solution 1:

d = { 'year': [2019,2020,2021,2020,2019,2021], 
      'age': [10,20,30,10,20,30], 
      'con': ['UK','UK','UK','US','US','US'],
      'population': [1,2,300,400,1000,2000]}
df = pd.DataFrame(data=d)
df2 = df.copy()

criteria = [df2['age'].between(0, 10), 
            df2['age'].between(11, 20), 
            df2['age'].between(21, 30)]

values = ['child', 'teen', 'work']

df2['con'] = df2['con']+'_'+np.select(criteria, values, 0)
df2['population'] = df.groupby(['con', 'age']).sum()\
                      .groupby(level=0).cumsum()\
                      .reset_index()['population']

final = pd.concat([df, df2])