Class Reference
%iFind.Rank.Abstract
Server:irisdocs1
Instance:IRISLATEST
User:UnknownUser
 
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  [%SYS] >  [%iFind] >  [Rank] >  [Abstract]
Private  Storage

This is the abstract superclass for all ranking algorithm implementations. In order to provide a rank or score for one or more records, an instance of this class is created and initialized with the search string and options. As part of this initialization, the search string will be parsed in the same way as it's done for the search operation itself and the resulting search tree is stored in the ParsedQuery.
Implementation-specific setup can be carried out by overriding the OnInitialize method, for example to prepare term weights and other reusable metrics that are common for all per-record calculations.
Then, the GetRecordScore method is invoked for every record, first invoking its OnBeforeGetRecordScore and then traversing the search tree's nodes one by one through calls to GetNodeScore, skipping the ones that are exclusion criteria (NOT). For each leaf node, GetLeafScore is invoked to obtain a score expressing how well that record matches that leaf node's search string.
These scores are then aggregated by taking the minimum value when nodes are ANDed and the maximum value when nodes are ORed, producing an overall score for the record, which can finally be amended through the OnGetRecordScore callback.

Subclasses should typically only override / implement the GetLeafScore and do any preparation or cleanup in the callback methods.

Inventory

Parameters Properties Methods Queries Indices ForeignKeys Triggers
2 11 10


Summary

Properties
ClassName IndexName IndexParams IndexType ParsedQuery
SearchArgs SearchOption SearchString

Methods
%AddToSaveSet %ClassIsLatestVersion %ClassName %ConstructClone
%DispatchClassMethod %DispatchGetModified %DispatchGetProperty %DispatchMethod
%DispatchSetModified %DispatchSetMultidimProperty %DispatchSetProperty %Extends
%GetParameter %IsA %IsModified %New
%NormalizeObject %ObjectModified %OriginalNamespace %PackageName
%RemoveFromSaveSet %SerializeObject %SetModified %ValidateObject
GetRecordScore Initialize

Subclasses

Parameters

• parameter OPERATORLOGICAND = "MIN";

Defines how weight scores of different subnodes of an AND node in the search tree are combined by the GetNodeScore method to provide an aggregated weight for the total. See OPERATORLOGICOR for a list of options.

• parameter OPERATORLOGICOR = "MAX";

Defines how weight scores of different subnodes of an OR node in the search tree are combined by the GetNodeScore method to provide an aggregated weight for the total. The different values are:

  • MAX: the highest weight of any sub-node is used as the weight of this composite node
  • MIN: the smallest weight of any sub-node is used as the weight of this composite node
  • SUM: the sum of all sub-node's weights is used as the weight of this composite node
  • AVG: the average of all sub-node's weights is used as the weight of this composite node

Properties

• property ClassName as %String [ Final,ReadOnly ];
Name of the class based on which' index records should be ranked
• property IndexName as %String [ Final,ReadOnly ];
The index based on which records should be ranked
• property IndexParams  [ MultiDimensional ];
An array containing all the index parameters of IndexName
• property IndexType as %String [ Final,ReadOnly ];
The index class of IndexName
• property ParsedQuery  [ MultiDimensional ];
The entire parsed query tree.
ParsedQuery([node ID], "o") = [operator: A|O|N]
ParsedQuery([node ID], "p") = [parent node ID]
ParsedQuery([node ID], "ch", [child node ID]) = [child node is negated]
ParsedQuery([node ID], "s") = n
ParsedQuery([node ID], "s", [leaf ID]) = [atomic string]
ParsedQuery([node ID], "s", [leaf ID], "n") = [atomic string is negated]
ParsedQuery([node ID], "s", [leaf ID], 1) = [left operator]
ParsedQuery([node ID], "s", [leaf ID], 2) = [right operator]
• property SearchArgs as %String [ Final,ReadOnly ];
Any additional search option arguments the ranker was initialized with. For example, when SearchOption = $$$IFSEARCHFUZZY, this property may contain the requested maximum edit distance.
• property SearchOption as %Integer [ Final,ReadOnly ];
The primary search option this ranker is initialized with (defaults to $$$IFSEARCHNORMAL)
• property SearchString as %String [ Final,ReadOnly ];
The full search string this ranker was initialized with.

Methods

• final method GetRecordScore(pRecordId As %RawString, Output pSC As %Status) as %Float

This method calculates the overall score for the given search string for one specific record by invoking GetNodeScore on the top-level node of the parsed search string. The resulting score can still be amended by OnGetRecordScore, order dto apply any record-level modifiers.

This method will also invoke the callback methods OnBeforeGetRecordScore and OnAfterGetRecordScore, which can be used to retrieve and clean up any record- related information required for the GetLeafScore implementation.

OnBeforeGetRecordScore implemenations may return a skip flag, instructing this code to skip the calls to GetNodeScore for this record.

• final method Initialize(pClassName As %String, pIndexName As %String, pSearchString As %String, pSearchOptions As %String = $$$IFSEARCHNORMAL) as %Status
This method initializes this ranker object for the given task, retrieving index metadata and parsing the search string


Copyright (c) 2019 by InterSystems Corporation. Cambridge, Massachusetts, U.S.A. All rights reserved. Confidential property of InterSystems Corporation.