Join Datasets Without Pandas Tools | Dataford Interview Questions

Without using pandas (dictionaries, lists, for loops), join the datasets and calculate average income by country.

Asked in the Jupyter live coding (Python) stage. Question 3 of 3; requires joining data and aggregating using plain Python data structures. For this SQL version, use the supplied customer and income tables.

Output

One row per country with at least one matched, non-null income
Columns: country_code, average_income
Round average_income to two decimal places and sort by country_code ascending

Schema

customer_profiles

Column	Type	Description
customer_idPK	INT	Unique customer identifier
country_code	VARCHAR(2)	Two-letter customer country code

customer_income

Column	Type	Description
income_idPK	INT	Unique income record identifier
customer_id	INT	Customer associated with the income record
annual_income	NUMERIC(12,2)	Reported annual income

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