[Solved] How can you group a list of products by category and then by price range (cheap: group_by calls?... How can you group a list of products by category and then by price range (cheap: group_by calls? | Ruby

Ruby - Enumerable and Collection Processing

How can you group a list of products by category and then by price range (cheap: <50, expensive: ≥50) using nested group_by calls?

products = [{name: 'Pen', category: 'Stationery', price: 10}, {name: 'Notebook', category: 'Stationery', price: 60}, {name: 'Mug', category: 'Kitchen', price: 40}]

Aproducts.group_by { |p| p[:category] }.transform_values { |arr| arr.group_by { |p| p[:price] < 50 ? :cheap : :expensive } }

Bproducts.group_by { |p| p[:price] < 50 ? :cheap : :expensive }.group_by { |p| p[:category] }

Cproducts.group_by { |p| [p[:category], p[:price] < 50 ? :cheap : :expensive] }

Dproducts.group_by { |p| p[:category] + p[:price].to_s }

Step-by-Step Solution

Solution:

Step 1: Group products by category
Use group_by on category to get a hash with categories as keys.
Step 2: For each category group, group by price range
Use transform_values to apply group_by again on price range within each category array.
Step 3: Check options
products.group_by { |p| p[:category] }.transform_values { |arr| arr.group_by { |p| p[:price] < 50 ? :cheap : :expensive } } correctly nests group_by calls. products.group_by { |p| p[:price] < 50 ? :cheap : :expensive }.group_by { |p| p[:category] } incorrectly chains group_by on the whole array twice. products.group_by { |p| [p[:category], p[:price] < 50 ? :cheap : :expensive] } groups by combined array key, not nested. products.group_by { |p| p[:category] + p[:price].to_s } concatenates strings, not grouping properly.
Final Answer:
products.group_by { |p| p[:category] }.transform_values { |arr| arr.group_by { |p| p[:price] < 50 ? :cheap : :expensive } } -> Option A
Quick Check:
Use transform_values for nested group_by [OK]

Quick Trick: Use transform_values to apply group_by on nested groups [OK]

Common Mistakes:

Chaining group_by incorrectly
Using combined keys instead of nested hashes
Concatenating strings instead of grouping

Master "Enumerable and Collection Processing" in Ruby

9 interactive learning modes - each teaches the same concept differently

Learn Why Deep Visual Try Challenge Project Recall Time

More Ruby Quizzes

How can you group a list of products by category and then by price range (cheap: group_by calls?

Step 1: Group products by category

Step 2: For each category group, group by price range

Step 3: Check options

Final Answer:

Quick Check:

Want More Practice?