column grouping (sum)

[metalray]

Dear Python Experts,

I am looking again at Daniel Breen's case study In [69]: he writes a function
called convert_housing_data_to_quarters().

http://danielbreen.net/projects/housing_...ege_towns/

The data is providing columns for every months from 1996-04 to 2016q3.
He is looping through the data to only consider columns from 2000q1 through 2016q3 and
sums them up in quarters. He does that in a nexted loop that
looks like it is dealing specifically with q3 and q4 of 2016.

for year in range(2000,2017):
   for quarter in range(1,5):
       
       if quarter == 4 and year == 2016:
           break
           
       new_column_name = '{0}q{1}'.format(year, quarter)
       begin_month = (quarter-1)*3 + 1
       end_month = quarter*3
       begin_column = '{0}-{1:02d}'.format(year,begin_month)
       end_column = '{0}-{1:02d}'.format(year,end_month)
       
       if quarter == 3 and year == 2016:
           new_column_name = '2016q3'
           begin_month = 6
           end_month = 8
           begin_column = '{0}-{1:02d}'.format(year,begin_month)
           end_column = '{0}-{1:02d}'.format(year,end_month)                
           
       data = housing_df.loc[:,begin_column:end_column]
           
       housing_df[new_column_name] = data.mean(axis = 1)

I wonder if there is an easier way. I would rahter fix the non-existing q3 and q4 problem
without a nested loop.

It would be really great if someone has a suggestion how to do that.
Maybe there is a function I dont know yet.