From Chaehyun

Collaborative Filtering

• input.txt
  • (user_id, item_id)

• map reduce 1 - change input format
  • user_id, Vector(item1, item2...)
  • user_item_list.txt

• map reduce 2 - minhash clustering
  • minhash_id \t user1, user2, user3 ...
  • clustering.txt

• map reduce 3 - generate recommendation
  • read clustering.txt and generate map in the memory
    • user1 - list(minhash1, minhash2, minhash3 ...)
    • user2 - list(minhash2, minhash3...)
  • mapper
    • read user_item_list.txt
    • emit each purchase record to each minhash cluster which a user belongs to
  • reducer
    • collect all records and make recommendations
  • output
    • user \t item1, item2 ...

• map reduce 4 - merge recommend list, sort items based on similarity, and print them