/*
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* 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.
*
* Copyright (c) 2006 - 2013 Pentaho Corporation and Contributors. All rights reserved.
*/
package org.pentaho.reporting.libraries.formula.function.math;
import java.math.BigDecimal;
import org.pentaho.reporting.libraries.formula.EvaluationException;
import org.pentaho.reporting.libraries.formula.FormulaContext;
import org.pentaho.reporting.libraries.formula.LibFormulaErrorValue;
import org.pentaho.reporting.libraries.formula.function.Function;
import org.pentaho.reporting.libraries.formula.function.ParameterCallback;
import org.pentaho.reporting.libraries.formula.lvalues.TypeValuePair;
import org.pentaho.reporting.libraries.formula.typing.coretypes.NumberType;
import org.pentaho.reporting.libraries.formula.util.NumberUtil;
/**
* This function returns the average of the number sequence.
*
* @author Cedric Pronzato
*/
public class AverageFunction implements Function
{
private static final long serialVersionUID = -5057715506050635450L;
private SumFunction sumFunction;
public AverageFunction()
{
sumFunction = new SumFunction();
}
protected AverageFunction(final SumFunction sumFunction)
{
this.sumFunction = sumFunction;
}
public String getCanonicalName()
{
return "AVERAGE";
}
public TypeValuePair evaluate(final FormulaContext context,
final ParameterCallback parameters)
throws EvaluationException
{
final TypeValuePair sum = sumFunction.evaluate(context, parameters);
final Number n = context.getTypeRegistry().convertToNumber(sum.getType(), sum.getValue());
if (n == null)
{
throw EvaluationException.getInstance(LibFormulaErrorValue.ERROR_INVALID_ARGUMENT_VALUE);
}
final BigDecimal divident = NumberUtil.getAsBigDecimal(n);
final BigDecimal divisor = new BigDecimal(parameters.getParameterCount());
final BigDecimal avg = NumberUtil.divide(divident, divisor);
return new TypeValuePair(NumberType.GENERIC_NUMBER, avg);
}
}