Syntax

feature_details::=

Analytic Syntax

feature_details_analytic::=

mining_attribute_clause::=

mining_analytic_clause::=

Purpose

FEATURE_DETAILS returns feature details for each row in the selection. The return value is an XML string that describes the attributes of the highest value feature or the specified feature_id.

topN

If you specify a value for topN, the function returns the N attributes that most influence the feature value. If you do not specify topN, the function returns the 5 most influential attributes.

DESC, ASC, or ABS

The returned attributes are ordered by weight. The weight of an attribute expresses its positive or negative impact on the value of the feature. A positive weight indicates a higher feature value. A negative weight indicates a lower feature value.

By default, FEATURE_DETAILS returns the attributes with the highest positive weight (DESC). If you specify ASC, the attributes with the highest negative weight are returned. If you specify ABS, the attributes with the greatest weight, whether negative or positive, are returned. The results are ordered by absolute value from highest to lowest. Attributes with a zero weight are not included in the output.

Syntax Choice

FEATURE_DETAILS can score the data in one of two ways: It can apply a mining model object to the data, or it can dynamically mine the data by executing an analytic clause that builds and applies one or more transient mining models. Choose Syntax or Analytic Syntax:

• Syntax — Use the first syntax to score the data with a pre-defined model. Supply the name of a feature extraction model.

• Analytic Syntax — Use the analytic syntax to score the data without a pre-defined model. Include INTO n, where n is the number of features to extract, and mining_analytic_clause, which specifies if the data should be partitioned for multiple model builds. The mining_analytic_clause supports a query_partition_clause and an order_by_clause. (See "analytic_clause::=".)

The syntax of the FEATURE_DETAILS function can use an optional GROUPING hint when scoring a partitioned model. See GROUPING Hint.

mining_attribute_clause

mining_attribute_clause identifies the column attributes to use as predictors for scoring. When the function is invoked with the analytic syntax, these predictors are also used for building the transient models. The mining_attribute_clause behaves as described for the PREDICTION function. (See "mining_attribute_clause".)

Example

This example uses the feature extraction model nmf_sh_sample to score the data. The query returns the three features that best represent customer 100002 and the attributes that most affect those features.

SELECT S.feature_id fid, value val,
       FEATURE_DETAILS(nmf_sh_sample, S.feature_id, 5 using T.*) det
   FROM
     (SELECT v.*, FEATURE_SET(nmf_sh_sample, 3 USING *) fset
         FROM mining_data_apply_v v
         WHERE cust_id = 100002) T,
   TABLE(T.fset) S
ORDER BY 2 DESC;
 
 FID    VAL  DET
---- ------  ------------------------------------------------------------------------------------
   5  3.492  <Details algorithm="Non-Negative Matrix Factorization" feature="5">
             <Attribute name="BULK_PACK_DISKETTES" actualValue="1" weight=".077" rank="1"/>
             <Attribute name="OCCUPATION" actualValue="Prof." weight=".062" rank="2"/>
             <Attribute name="BOOKKEEPING_APPLICATION" actualValue="1" weight=".001" rank="3"/>
             <Attribute name="OS_DOC_SET_KANJI" actualValue="0" weight="0" rank="4"/>
             <Attribute name="YRS_RESIDENCE" actualValue="4" weight="0" rank="5"/>
             </Details>
   3  1.928  <Details algorithm="Non-Negative Matrix Factorization" feature="3">
             <Attribute name="HOUSEHOLD_SIZE" actualValue="2" weight=".239" rank="1"/>
             <Attribute name="CUST_INCOME_LEVEL" actualValue="L: 300\,000 and above" 
              weight=".051" rank="2"/>
             <Attribute name="FLAT_PANEL_MONITOR" actualValue="1" weight=".02" rank="3"/>
             <Attribute name="HOME_THEATER_PACKAGE" actualValue="1" weight=".006" rank="4"/>
             <Attribute name="AGE" actualValue="41" weight=".004" rank="5"/>
             </Details>
   8   .816  <Details algorithm="Non-Negative Matrix Factorization" feature="8">
             <Attribute name="EDUCATION" actualValue="Bach." weight=".211" rank="1"/>
             <Attribute name="CUST_MARITAL_STATUS" actualValue="NeverM" weight=".143" rank="2"/>
             <Attribute name="FLAT_PANEL_MONITOR" actualValue="1" weight=".137" rank="3"/>
             <Attribute name="CUST_GENDER" actualValue="F" weight=".044" rank="4"/>
             <Attribute name="BULK_PACK_DISKETTES" actualValue="1" weight=".032" rank="5"/>
             </Details>

Analytic Example

This example dynamically maps customer attributes into six features and returns the feature mapping for customer 100001.

SELECT feature_id, value
  FROM (
     SELECT cust_id, feature_set(INTO 6 USING *) OVER () fset
        FROM mining_data_apply_v),
  TABLE (fset)
  WHERE cust_id = 100001
  ORDER BY feature_id;
 
FEATURE_ID    VALUE
---------- --------
         1    2.670
         2     .000
         3    1.792
         4     .000
         5     .000
         6    3.379