📊 Ranking Function (HGrid247)

🔍 Definition

Ranking is a function to rank data that has been:

1. Grouped (GroupBy)
2. Sorted (ascending / descending)

➡️ Rank is determined based on the sorting result field

⚙️ Parameter

🎯 Max Rank

• Determine the maximum limit of the resulting ranking
• Only data with:

      rank ≤ Max Rank
      

which will be passed on to the next assembly

📌 If not filled in:

➡️ All data remains out (unrestricted)

📥 Input & 📤 Output

Input

• All fields from the previous process (usually the result of GroupBy + Sort)

Output

• All input fields
  ➕ additional new fields:

  ranking    
  

🧠 How it works

For example, the data is already sorted:

    category	views
    ---------------------
    A           90
    A           100
    A           80

➡️ After Ranking:

    category	views	ranking
    --------------------------
    A           100	1
    A           90	2
    A           80	3

🧪 Case Example (Top N per Group)

🎯 Case Study:

Displays the Top 2 videos with the most views per category 🔄 Workflow

1. Group By → category
2. Sort → views DESC
3. Ranking (Max Rank = 2) 📊 Results:

       category	video	views	ranking
       -----------------------------------
       Music	V1	1000	1
       Music	V2	900	2
       Music	V3	800	❌ (not out)
   

   🔥 Important Insights

   1. Ranking requires sorting

   Without sorting:
   ➡️ ranking becomes meaningless

   2. Used for Top-N

   Common use cases:

   • Top 10 best-selling products
   • Top 5 video trending
   • Top customer per region