net.esper.view.stat
Class WeightedAverageView

java.lang.Object
  extended by net.esper.view.ViewSupport
      extended by net.esper.view.stat.WeightedAverageView
All Implemented Interfaces:
java.lang.Iterable<EventBean>, EventCollection, View, Viewable

public final class WeightedAverageView
extends ViewSupport

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
 
Fields inherited from class net.esper.view.ViewSupport
parent
 
Constructor Summary
WeightedAverageView()
          Default constructor - required by all views to adhere to the Java bean specification.
WeightedAverageView(java.lang.String fieldNameX, java.lang.String fieldNameWeight)
          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
 java.lang.String attachesTo(Viewable parentView)
          Return null if the view will accept being attached to a particular object.
 EventType getEventType()
          Provides metadata information about the type of object the event collection contains.
 java.lang.String getFieldNameWeight()
          Returns the name of the field supplying the weight values.
 java.lang.String getFieldNameX()
          Returns the name of the field supplying the X values.
 java.util.Iterator<EventBean> iterator()
          Allows iteration through all elements in this event collection.
 void setFieldNameWeight(java.lang.String fieldNameWeight)
          Sets the name of the field supplying the weight values.
 void setFieldNameX(java.lang.String fieldNameX)
          Sets the name of the field supplying the X values.
 void setParent(Viewable parent)
          Called when the View is added to a Viewable object.
 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 net.esper.view.ViewSupport
addView, dumpChildViews, dumpUpdateParams, findDescendent, getParent, getViews, hasViews, removeView, shallowCopyView, updateChildren, updateChildren
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

WeightedAverageView

public WeightedAverageView()
Default constructor - required by all views to adhere to the Java bean specification.


WeightedAverageView

public WeightedAverageView(java.lang.String fieldNameX,
                           java.lang.String fieldNameWeight)
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.

Parameters:
fieldNameX - is the name of the field within the parent view to use to get numeric data points for this view to compute the average for.
fieldNameWeight - is the field name for the weight to apply to each data point
Method Detail

setParent

public void setParent(Viewable parent)
Description copied from interface: View
Called when the View is added to a Viewable object.

Specified by:
setParent in interface View
Overrides:
setParent in class ViewSupport
Parameters:
parent - is the parent that this view is a child of

getFieldNameX

public final java.lang.String getFieldNameX()
Returns the name of the field supplying the X values.

Returns:
field name supplying X data points

setFieldNameX

public final void setFieldNameX(java.lang.String fieldNameX)
Sets the name of the field supplying the X values.

Parameters:
fieldNameX - field name supplying X data points

getFieldNameWeight

public final java.lang.String getFieldNameWeight()
Returns the name of the field supplying the weight values.

Returns:
field name supplying weight

setFieldNameWeight

public final void setFieldNameWeight(java.lang.String fieldNameWeight)
Sets the name of the field supplying the weight values.

Parameters:
fieldNameWeight - field name supplying weight

attachesTo

public final java.lang.String attachesTo(Viewable parentView)
Description copied from interface: View
Return null if the view will accept being attached to a particular object.

Parameters:
parentView - is the potential parent for this view
Returns:
null if this view can successfully attach to the parent, an error message if it cannot.

update

public final 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.

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.

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.

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