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      DescendingIndex
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      DescendingIndex

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      Article summary

      General: DescendingIndex

      Assigns an integer to each unique value in the field, working in reverse order.

      Creates an Integer field with values N to 1, where N is the number of discrete values in the source field. 

      Purpose

      Use this function to:
      • Reverse sort unique values in a field
      • Transform a field into an integer for use with integer engineering functions

      Return Value

      PropertyValue
      FieldTypeInteger / LongInteger
      FieldSizeLow / Med / High 
      DataTypeDiscrete 
      DataSizeByte / Short / Integer 


      Example Return Value: N......1


      Parameters

      ParameterJSONDescription
      Table“targetTable”: “MyTableName”The target table on which the new field will be created
      Filter“dataset”: {DataSet_JSON}Optional.   If a filter is applied, records not in the filter recordset will be returned as null.
      Use a filter to exclude records from the source field. If the source field has too many discrete values to create a DescendingIndex, excluding some records may reduce the index size enough for a discrete index to be created.
      To specify records to Exclude:
      1. Select the records to be excluded and drag them into the HotBar
      2. Right-click and choose the Invert function
      3. Add the resulting Recordset as a filter
      Function"function":"descendingindex"DescendingIndex
      Source Field“p1”: “SourceFieldName”Required.  The Discrete (i.e., non-continuous) field from which to create the index.

      If it is necessary to create an index from a continuous field, depending on the field contents, the CONCAT function can sometimes be used to create a discrete copy of the continuous field.

      If the continuous field is a numeric field, the output from the CONCAT function can be cast back into a numeric field using the WILDICAST function. 

      Strings can be cast as date fields using the DateFromString function.

      Treat Null as Zero"nullIsZero": true
      "nullIsZero": false

      		True/False.
      Default = False
      If true, then any null values in the input fields will be treated as if they have a value of 0.

      JSON Sample

      {
  "method": "BuildBakedField",
  "project": "D3",
  "targetTable": "transactions",
  "overwrite": true,
  "name": "DescIndex_date",
  "function": "descendingindex",
  "p1": "date"
}

      Usage Notes

      The function only works on Discrete source fields.    See CONCAT, WILDICAST and DATEFROMSTRING if it is necessary to create an index from a Continuous field. 

      If a filter is applied, records which are not in the filter will be stored as NULL in the new field. Applying a filter may reduce the number of discrete values in a continuous field sufficiently to create a discrete index.

      The maximum number of discrete values in a discrete index is 1,000,000

      For more information on field and data types, see  Field Types and Data Types

      See Also:   

      • Engineering | Expression Field
      • CONCAT   (String Function)
      • WILDICAST (String Function)
      • DATEFROMSTRING   (String Function)

      Example

      ExampleDetails
      DescriptionCreate a descending index from average spend
      Input
      • Table: = [customer]
      • Filter: = [No Filter]
      • Function: = DescendingIndex
      • Source Field:= avgl_spend
      • Name: =spend_descend
      Sample




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