er.extensions.foundation
Class ERXArrayUtilities.MedianOperator

java.lang.Object
  er.extensions.foundation.ERXArrayUtilities.MedianOperator

All Implemented Interfaces:

com.webobjects.foundation.NSArray.Operator

Enclosing class:

ERXArrayUtilities

public static class ERXArrayUtilities.MedianOperator
extends java.lang.Object
implements com.webobjects.foundation.NSArray.Operator

Define an NSArray.Operator for the key median.

This allows for key value paths like:

• myArray.valueForKey("@median.payment.amount");
• myArray.valueForKey("payment.@median.amount");
• myArray.valueForKey("payment.amount.@median");

which return the median of the array elements at the given key path. The median is the value for which half of the elements are above and half the elements are below. As such, an array sort is needed and this might be very costly depending of the size of the array.

The @median operator applies to the array of objects to its left if it is the last key in the path. Otherwise it applies to the end of the keypath to its right. It should not be followed by an array or any other array operators. This is because it does not call valueForKeyPath on the array to its left, but instead loops through the values of the array to its left, calling valueForKeyPath on the individual array values instead. This behavior is consistent with Apple's standard NSArray operators.

Constructor Summary

ERXArrayUtilities.MedianOperator()
public empty constructor

Method Summary

java.lang.Object

compute(com.webobjects.foundation.NSArray<?> array, java.lang.String keypath) returns the median value for the values of the keypath.

Methods inherited from class java.lang.Object

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

Constructor Detail

ERXArrayUtilities.MedianOperator

public ERXArrayUtilities.MedianOperator()

public empty constructor

Method Detail

compute

public java.lang.Object compute(com.webobjects.foundation.NSArray<?> array,
                                java.lang.String keypath)

returns the median value for the values of the keypath.

Specified by:

compute in interface com.webobjects.foundation.NSArray.Operator

Parameters:

array - array to be checked.

keypath - path to numeric values

Returns:

median value