FEATURE_SET

Syntax

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Description of the illustration feature_set.gif

mining_attribute_clause:=

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Description of the illustration mining_attribute_clause.gif

Purpose

This function is for use with feature extraction models that have been created using the DBMS_DATA_MINING package or with the Oracle Data Mining Java API. It returns a varray of objects containing all possible features. Each object in the varray is a pair of scalar values containing the feature ID and the feature value. The object fields are named FEATURE­_ID and VALUE, and both are Oracle NUMBER.

The optional topN argument is a positive integer that restricts the set of features to those that have one of the top N values. If there is a tie at the Nth value, the database still returns only N values. If you omit this argument, then the function returns all features.

The optional cutoff argument restricts the returned features to only those that have a feature value greater than or equal to the specified cutoff. To filter only by cutoff, specify NULL for topN and the desired cutoff for cutoff.

The mining_attribute_clause behaves as described for the PREDICTION function. Please refer to mining_attribute_clause.

Examples

The following example lists the top features corresponding to a given customer record (based on match quality), and determines the top attributes for each feature (based on coefficient > 0.25).

This example and the prerequisite data mining operations, including the creation of the model, views, and type, can be found in the demo file $ORACLE_HOME/rdbms/demo/dmnmdemo.sql. General information on data mining demo files is available in Oracle Data Mining Administrator's Guide. The example is presented here to illustrate the syntactic use of the function.

WITH
feat_tab AS (
SELECT F.feature_id fid,
 A.attribute_name attr,
 TO_CHAR(A.attribute_value) val,
 A.coefficient coeff
 FROM TABLE(DBMS_DATA_MINING.GET_MODEL_DETAILS_NMF('nmf_sh_sample')) F,
 TABLE(F.attribute_set) A
 WHERE A.coefficient > 0.25
),
feat AS (
SELECT fid,
 CAST(COLLECT(Featattr(attr, val, coeff))
 AS Featattrs) f_attrs
 FROM feat_tab
GROUP BY fid
),
cust_10_features AS (
SELECT T.cust_id, S.feature_id, S.value
 FROM (SELECT cust_id, FEATURE_SET(nmf_sh_sample, 10 USING *) pset
 FROM nmf_sh_sample_apply_prepared
 WHERE cust_id = 100002) T,
 TABLE(T.pset) S
)
SELECT A.value, A.feature_id fid,
 B.attr, B.val, B.coeff
 FROM cust_10_features A,
 (SELECT T.fid, F.*
 FROM feat T,
 TABLE(T.f_attrs) F) B
 WHERE A.feature_id = B.fid
ORDER BY A.value DESC, A.feature_id ASC, coeff DESC, attr ASC, val ASC;
 VALUE FID ATTR VAL COEFF
-------- ---- ------------------------- -------------------- -------
 6.8409 7 YRS_RESIDENCE 1.3879
 6.8409 7 BOOKKEEPING_APPLICATION .4388
 6.8409 7 CUST_GENDER M .2956
 6.8409 7 COUNTRY_NAME United States of Ame .2848
 rica
 
 6.4975 3 YRS_RESIDENCE 1.2668
 6.4975 3 BOOKKEEPING_APPLICATION .3465
 6.4975 3 COUNTRY_NAME United States of Ame .2927
 rica
 
 6.4886 2 YRS_RESIDENCE 1.3285
 6.4886 2 CUST_GENDER M .2819
 6.4886 2 PRINTER_SUPPLIES .2704
 6.3953 4 YRS_RESIDENCE 1.2931
 5.9640 6 YRS_RESIDENCE 1.1585
 5.9640 6 HOME_THEATER_PACKAGE .2576
 5.2424 5 YRS_RESIDENCE 1.0067
 2.4714 8 YRS_RESIDENCE .3297
 2.3559 1 YRS_RESIDENCE .2768
 2.3559 1 FLAT_PANEL_MONITOR .2593
 
17 rows selected.