Rank Component
Rank Component
Allows the user to determine the rank of a value in a group of values.
Properties
Property | Setting | Description |
---|---|---|
Name | Text | The descriptive name for the component. |
Include Input Columns | Yes/No | Defines whether the component passes all input columns into the output. |
Partition Data | List of Columns | Defines how the input data is partitioned in order to perform the rank calculation. The calculation is then performed on each partition. |
Ordering within partitions | Input Column | The input column name for sorting within the partitioned data. Note: you can drag to reorder |
Ordering | The order of the sorting: Ascending (Asc) or Descending (Desc) | |
Functions | Window Function |
Rank - determines the rank of a value in a group of values. Dense Rank - determines the rank of a value in a group of values. The Dense Rank function differs from rank in one respect: If two or more rows tie, there is no gap in the sequence of ranked values. Cumulative Distribution - determines the cumulative distribution of a value within a window or partition. Percent Rank - Calculates the percent rank of a given row. Row Number - Determines the ordinal number of the current row within a group of rows, counting from 1. |
Output Column | The name of the output column that the window function will create. |
Strategy
Example
In this example we wish to determine the longest flight by airtime for a given year. Luckily, we have a table full of flight data already. The job is set up as below.
The filter component is used to filter any null values from the data where airtime was not properly recorded. The remaining rows pass on to the Rank component that is set up as shown below.
'Include Input Columns' is set to Yes so that all input columns are also output. The data is partitioned by year; in this case, this means that our output data will rank airtimes for the year 2000 followed by airtimes for the year 1999 and so on.
The 'Ordering within Partitions' property is the key to our ranking and is set to rank by airtime, descending.
Finally, the 'Rank' function is chosen and the new output column is called 'Airtime Rank'. This new column will show the rank of that particular row for that year.
The output data can now be sampled from the Rank component and should reveal the longest airtime at the top of the sample.