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Oracle® Database SQL Reference 10g Release 2 (10.2) Part Number B14200-02 |
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# FEATURE_SET

Syntax

Description of the illustration feature_set.gif

mining_attribute_clause:=

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.

See Also: Oracle Data Mining Concepts for detailed information on Oracle Data Mining features Oracle Data Mining Administrator's Guide for information on the demo programs available in the code Oracle Data Mining Application Developer's Guide for information on writing Oracle Data Mining applications

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.