38.5 CLUSTER_SET
Syntax
cluster_set::=
Analytic Syntax
cluster_set_analytic::=
mining_attribute_clause::=
mining_analytic_clause::=
See Also:
"Analytic Functions" for information on the syntax, semantics, and restrictions of mining_analytic_clause
Purpose
CLUSTER_SET
returns a set of cluster ID and probability pairs for each row in the selection. The return value is a varray of objects with field names CLUSTER_ID
and PROBABILITY
. The cluster identifier is an Oracle NUMBER
; the probability is BINARY_DOUBLE
.
topN and cutoff
You can specify topN
and cutoff
to limit the number of clusters returned by the function. By default, both topN
and cutoff
are null and all clusters are returned.
-
topN
is theN
most probable clusters. If multiple clusters share theN
th probability, then the function chooses one of them. -
cutoff
is a probability threshold. Only clusters with probability greater than or equal tocutoff
are returned. To filter bycutoff
only, specifyNULL
fortopN
.
To return up to the N
most probable clusters that are greater than or equal to cutoff
, specify both topN
and cutoff
.
Syntax Choice
CLUSTER_SET
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 clustering model.
-
Analytic Syntax — Use the analytic syntax to score the data without a pre-defined model. Include
INTO
n
, wheren
is the number of clusters to compute, andmining_analytic_clause
, which specifies if the data should be partitioned for multiple model builds. Themining_analytic_clause
supports aquery_partition_clause
and anorder_by_clause
. (See "analytic_clause::=".)
The syntax of the CLUSTER_SET
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".)
See Also:
-
Oracle Data Mining User's Guide for information about scoring.
-
Oracle Data Mining Concepts for information about clustering.
Note:
The following example is excerpted from the Data Mining sample programs. For more information about the sample programs, see Appendix A in Oracle Data Mining User's Guide.
Example
This example lists the attributes that have the greatest impact (more that 20% probability) on cluster assignment for customer ID 100955. The query invokes the CLUSTER_DETAILS
and CLUSTER_SET
functions, which apply the clustering model em_sh_clus_sample
.
SELECT S.cluster_id, probability prob, CLUSTER_DETAILS(em_sh_clus_sample, S.cluster_id, 5 USING T.*) det FROM (SELECT v.*, CLUSTER_SET(em_sh_clus_sample, NULL, 0.2 USING *) pset FROM mining_data_apply_v v WHERE cust_id = 100955) T, TABLE(T.pset) S ORDER BY 2 DESC; CLUSTER_ID PROB DET ---------- ----- ------------------------------------------------------------------------------ 14 .6761 <Details algorithm="Expectation Maximization" cluster="14"> <Attribute name="AGE" actualValue="51" weight=".676" rank="1"/> <Attribute name="HOME_THEATER_PACKAGE" actualValue="1" weight=".557" rank="2"/> <Attribute name="FLAT_PANEL_MONITOR" actualValue="0" weight=".412" rank="3"/> <Attribute name="Y_BOX_GAMES" actualValue="0" weight=".171" rank="4"/> <Attribute name="BOOKKEEPING_APPLICATION" actualValue="1" weight="-.003"rank="5"/> </Details> 3 .3227 <Details algorithm="Expectation Maximization" cluster="3"> <Attribute name="YRS_RESIDENCE" actualValue="3" weight=".323" rank="1"/> <Attribute name="BULK_PACK_DISKETTES" actualValue="1" weight=".265" rank="2"/> <Attribute name="EDUCATION" actualValue="HS-grad" weight=".172" rank="3"/> <Attribute name="AFFINITY_CARD" actualValue="0" weight=".125" rank="4"/> <Attribute name="OCCUPATION" actualValue="Crafts" weight=".055" rank="5"/> </Details>