Rank Transformation

Explain about Rank Transformation

Rank Transformation

This is a type active Transformation which allows you to calculate the top and bottom performers.

It is created with following type of ports

1. Input port

2. Output    

3.Variable port (V)

4.Rank port (R)

Rank port: The port which is participated in rank calculation is known as rank port. It is only an output port

Variable port: A port which allows you to develop expressions to store the data temporarily for rank calculation is known as variable port.

Set the following properties to calculate the ranks.         

1. Top/bottom                 

2.Number of ranks

Group Functions

A Rank transformation can also support to group information. For example if you want to see the top 10 expensive products by a company, then you need to define a group for each company. You can do this by selecting GROUP BY column in the properties of the Rank transformation. You can select GROUP BY for only one input column. 

If two products have the same ranking the next rank will be skipped. Example

RankIndex          Product            Cost
    
        1                       A                    1890
        2                       B                    1670        2                       C                    1670
        4                       D                    1537


For an exercise on this transformation check this   http://prashanthobiee.blogspot.in/2012/12/exercise-to-implement-filter-rank-and.html