CHarmonicMean.java
/*
* @cond LICENSE
* ######################################################################################
* # LGPL License #
* # #
* # This file is part of the LightJason AgentSpeak(L++) #
* # Copyright (c) 2015-19, LightJason (info@lightjason.org) #
* # This program is free software: you can redistribute it and/or modify #
* # it under the terms of the GNU Lesser General Public License as #
* # published by the Free Software Foundation, either version 3 of the #
* # License, or (at your option) any later version. #
* # #
* # This program is distributed in the hope that it will be useful, #
* # but WITHOUT ANY WARRANTY; without even the implied warranty of #
* # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the #
* # GNU Lesser General Public License for more details. #
* # #
* # You should have received a copy of the GNU Lesser General Public License #
* # along with this program. If not, see http://www.gnu.org/licenses/ #
* ######################################################################################
* @endcond
*/
package org.lightjason.agentspeak.action.builtin.math;
import org.lightjason.agentspeak.action.builtin.IBuiltinAction;
import org.lightjason.agentspeak.language.CCommon;
import org.lightjason.agentspeak.language.CRawTerm;
import org.lightjason.agentspeak.language.ITerm;
import org.lightjason.agentspeak.language.execution.IContext;
import org.lightjason.agentspeak.language.fuzzy.CFuzzyValue;
import org.lightjason.agentspeak.language.fuzzy.IFuzzyValue;
import javax.annotation.Nonnegative;
import javax.annotation.Nonnull;
import java.util.List;
import java.util.stream.Stream;
/**
* action for harmonic mean.
* The action calculates \f$ \frac{i}{\sum_{i} \frac{1}{x_i}} \f$
* over all unflatten arguments, action fails never
*
* {@code G = math/harmonicmean( 1, 3, 9, [10, [11, 12]] );}
* @see https://en.wikipedia.org/wiki/Average
*/
public final class CHarmonicMean extends IBuiltinAction
{
/**
* serial id
*/
private static final long serialVersionUID = 512098153369001644L;
@Nonnegative
@Override
public final int minimalArgumentNumber()
{
return 1;
}
@Nonnull
@Override
public final IFuzzyValue<Boolean> execute( final boolean p_parallel, @Nonnull final IContext p_context,
@Nonnull final List<ITerm> p_argument, @Nonnull final List<ITerm> p_return )
{
p_return.add(
CRawTerm.from(
CHarmonicMean.apply(
CCommon.flatten( p_argument ).count(),
CCommon.flatten( p_argument )
.map( ITerm::<Number>raw )
.mapToDouble( Number::doubleValue )
.boxed()
)
)
);
return CFuzzyValue.from( true );
}
/**
* calculate harmonic mean
*
* @param p_count number of elements
* @param p_values value stream
* @return harmonic mean
*/
private static double apply( final double p_count, final Stream<Double> p_values )
{
return p_count / p_values.mapToDouble( i -> 1.0 / i ).sum();
}
}