io.warp10.continuum.gts

Class DISCORDS

java.lang.Object

io.warp10.script.NamedWarpScriptFunction

io.warp10.script.GTSStackFunction

io.warp10.continuum.gts.DISCORDS

All Implemented Interfaces:

WarpScriptStackFunction

public class DISCORDS
extends GTSStackFunction

Detects discords in a GTS instance. The way discords are detected is by computing a histogram of bSAX symbols. Those symbols with the lowest frequency are suspects for being discords, each one is compared to its closest neighbours (we heuristically assume that bSAX symbols appearing close in lexicographic order are the ones containing the nearest neighbours). The 'count' suspects with highest distance to nearest neighbors are considered the discords. The expected parameters on the stack are: 6: GTS 5: long windowLen 4: long wordLen (must divide windowLen) 3: long alphabetSize (must be a power of 2) 2: long count, number of discords to identify 1: boolean mayOverride

Constructor Summary

Constructors

Constructor and Description
DISCORDS(java.lang.String name, boolean standardizePAA)

Method Summary

Modifier and Type	Method and Description
static GeoTimeSerie	discords(GeoTimeSerie gts, int windowLen, int wordLen, int alphabetSize, int count, boolean mayOverlap, double distRatio, boolean standardizePAA)
protected java.lang.Object	gtsOp(java.util.Map<java.lang.String,java.lang.Object> params, GeoTimeSerie gts) Method to apply to individual GTS instances
protected java.util.Map<java.lang.String,java.lang.Object>	retrieveParameters(WarpScriptStack stack) Method which extracts the parameters from the top of the stack

Methods inherited from class io.warp10.script.GTSStackFunction

apply

Methods inherited from class io.warp10.script.NamedWarpScriptFunction

getName, refSnapshot, setName, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DISCORDS

public DISCORDS(java.lang.String name,
                boolean standardizePAA)

Method Detail

gtsOp

protected java.lang.Object gtsOp(java.util.Map<java.lang.String,java.lang.Object> params,
                                 GeoTimeSerie gts)
                          throws WarpScriptException

Description copied from class: GTSStackFunction

Method to apply to individual GTS instances

Specified by:

gtsOp in class GTSStackFunction

Throws:

WarpScriptException

retrieveParameters

protected java.util.Map<java.lang.String,java.lang.Object> retrieveParameters(WarpScriptStack stack)
                                                                       throws WarpScriptException

Description copied from class: GTSStackFunction

Method which extracts the parameters from the top of the stack

Specified by:

retrieveParameters in class GTSStackFunction

Throws:

WarpScriptException

discords

public static final GeoTimeSerie discords(GeoTimeSerie gts,
                                          int windowLen,
                                          int wordLen,
                                          int alphabetSize,
                                          int count,
                                          boolean mayOverlap,
                                          double distRatio,
                                          boolean standardizePAA)
                                   throws WarpScriptException

Parameters:

gts - GTS instance to analyze

windowLen - Number of ticks in sliding window

wordLen - Size of SAX symbols

alphabetSize - Size of SAX alphabet (MUST be a power of 2)

count - Maximum number of discords to identify

mayOverlap - Flag indicating whether or not identified discords may overlap

distRatio - Maximum tolerable ratio between NN distances. Once an NN dist is smaller than 'distRatio' times the previous candidate, exit

Throws:

WarpScriptException