com.espertech.esper.view.stat
Class WeightedAverageView

java.lang.Object
  com.espertech.esper.view.ViewSupport
      com.espertech.esper.view.stat.WeightedAverageView

All Implemented Interfaces:

CloneableView, DerivedValueView, EventCollection, GroupableView, View, Viewable, java.lang.Iterable<EventBean>

public class WeightedAverageView
extends ViewSupport
implements CloneableView, DerivedValueView

View for computing a weighted average. The view uses 2 fields within the parent view to compute the weighted average. The X field and weight field. In a price-volume example it calculates the volume-weighted average price as (sum(price * volume) / sum(volume)). Example: weighted_avg("price", "volume")

Field Summary

protected double	currentValue
protected java.lang.Object[]	lastValuesEventNew
protected double	sumW
protected double	sumXtimesW

Fields inherited from class com.espertech.esper.view.ViewSupport

EMPTY_VIEW_ARRAY, parent

Constructor Summary

WeightedAverageView(WeightedAverageViewFactory viewFactory, AgentInstanceViewFactoryChainContext agentInstanceContext)
Constructor requires the name of the field to use in the parent view to compute the weighted average on, as well as the name of the field in the parent view to get the weight from.

Method Summary

View	cloneView() Duplicates the view.
static EventType	createEventType(StatementContext statementContext, StatViewAdditionalProps additionalProps, int streamNum) Creates the event type for this view.
double	getCurrentValue()
EventType	getEventType() Provides metadata information about the type of object the event collection contains.
ExprNode	getFieldNameWeight() Returns the expression supplying the weight values.
ExprNode	getFieldNameX() Returns the expression supplying the X values.
java.lang.Object[]	getLastValuesEventNew()
double	getSumW()
double	getSumXtimesW()
ViewFactory	getViewFactory()
java.util.Iterator<EventBean>	iterator() Allows iteration through all elements in this event collection.
void	setCurrentValue(double currentValue)
void	setLastValuesEventNew(java.lang.Object[] lastValuesEventNew)
void	setSumW(double sumW)
void	setSumXtimesW(double sumXtimesW)
java.lang.String	toString()
void	update(EventBean[] newData, EventBean[] oldData) Notify that data has been added or removed from the Viewable parent.

Methods inherited from class com.espertech.esper.view.ViewSupport

addView, addView, dumpChildViews, dumpUpdateParams, dumpUpdateParams, findDescendent, findViewIndex, getParent, getViews, hasViews, removeAllViews, removeView, removeView, setParent, updateChildren, updateChildren

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.espertech.esper.view.View

getParent, setParent

Methods inherited from interface com.espertech.esper.view.Viewable

addView, getViews, hasViews, removeAllViews, removeView

Field Detail

sumXtimesW

protected double sumXtimesW

sumW

protected double sumW

currentValue

protected double currentValue

lastValuesEventNew

protected java.lang.Object[] lastValuesEventNew

Constructor Detail

WeightedAverageView

public WeightedAverageView(WeightedAverageViewFactory viewFactory,
                           AgentInstanceViewFactoryChainContext agentInstanceContext)

Constructor requires the name of the field to use in the parent view to compute the weighted average on, as well as the name of the field in the parent view to get the weight from. compute the average for.

Method Detail

cloneView

public View cloneView()

Description copied from interface: CloneableView

Duplicates the view.

Expected to return a same view in initialized state for grouping.

Specified by:

cloneView in interface CloneableView

getFieldNameX

public final ExprNode getFieldNameX()

Returns the expression supplying the X values.

Returns:

expression supplying X data points

getFieldNameWeight

public final ExprNode getFieldNameWeight()

Returns the expression supplying the weight values.

Returns:

expression supplying weight

update

public void update(EventBean[] newData,
                   EventBean[] oldData)

Description copied from interface: View

Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view. If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification. When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

Specified by:

update in interface View

Parameters:

newData - is the new data that has been added to the parent view

oldData - is the old data that has been removed from the parent view

getEventType

public final EventType getEventType()

Description copied from interface: EventCollection

Provides metadata information about the type of object the event collection contains.

Specified by:

getEventType in interface EventCollection

Returns:

metadata for the objects in the collection

iterator

public final java.util.Iterator<EventBean> iterator()

Description copied from interface: EventCollection

Allows iteration through all elements in this event collection. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.

Specified by:

iterator in interface EventCollection

Specified by:

iterator in interface java.lang.Iterable<EventBean>

Returns:

an iterator which will go through all current elements in the collection.

toString

public final java.lang.String toString()

Overrides:

toString in class java.lang.Object

createEventType

public static EventType createEventType(StatementContext statementContext,
                                        StatViewAdditionalProps additionalProps,
                                        int streamNum)

Creates the event type for this view.

Parameters:

statementContext - is the event adapter service

Returns:

event type of view

getSumXtimesW

public double getSumXtimesW()

setSumXtimesW

public void setSumXtimesW(double sumXtimesW)

getSumW

public double getSumW()

setSumW

public void setSumW(double sumW)

getCurrentValue

public double getCurrentValue()

setCurrentValue

public void setCurrentValue(double currentValue)

getLastValuesEventNew

public java.lang.Object[] getLastValuesEventNew()

setLastValuesEventNew

public void setLastValuesEventNew(java.lang.Object[] lastValuesEventNew)

getViewFactory

public ViewFactory getViewFactory()

Specified by:

getViewFactory in interface GroupableView