46. Sorted Distinct Purchase List

Difficulty: Medium · Topics: Arrays, Aggregations

For each customer_id in purchases, return products, the distinct products they bought as an array sorted alphabetically, and product_count, the number of distinct products.

Row order does not matter; column names must match. Your code is graded on 3 test cases, including hidden edge cases.

Sample data

purchases

customer_id	product
1	pear
1	apple
1	pear
2	kiwi

Expected output

customer_id	products	product_count
1	[apple, pear]	2
2	[kiwi]	1

Hints

Hint 1

F.collect_set gathers distinct values per group, in no guaranteed order.

Hint 2

Wrap it in F.sort_array for a deterministic, sorted array.

Hint 3

F.size gives the array length.

PySpark functions you'll practise

• groupBy
• agg
• collect_set
• sort_array
• size

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Topics: Window Functions · Joins · Aggregations · Pivot, Unpivot & Rollup · Arrays · Null Handling · Conditional Logic · Dates · Filtering & Selection · Strings

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