How to do pivot operation on multiple columns on python pandas or big query. Preferably on big query

Question

original data:

how the data would look like after required transformation:

I have tried melt function in python pandas, but I am only able to pivot on one column. I am sure I must be missing something.

Answer 1

Below is for BigQuery Standard SQL

execute immediate (
with types as (
  select 
    array_to_string(types, ',') values_list,
    regexp_replace(array_to_string(types, ','), r'([^,]+)', r'"\1"') columns_list
  from (
    select regexp_extract_all(to_json_string(t), r'"([^""]+)":') types
    from (
      select * except(Country, Branch, Category)
      from `project.dataset.your_table` limit 1
    ) t
  )
), categories as (
  select distinct Category  
  from `project.dataset.your_table`
)
select '''
select Country, Branch, Output, ''' || 
  (select string_agg(''' 
  max(if(Category = "''' || Category || '''", val, null)) as ''' || Category ) 
  from categories)
|| ''' 
from (
  select Country, Branch, Category, 
    type[offset(offset)] Output, val 
  from `project.dataset.your_table` t,
  unnest([''' || values_list || ''']) val with offset,
  unnest([struct([''' || columns_list || '''] as type)])
)
group by Country, Branch, Output
'''
from types
);   

if applied to sample data in your question - output is