001 /** 002 * ========================================= 003 * LibFormula : a free Java formula library 004 * ========================================= 005 * 006 * Project Info: http://reporting.pentaho.org/libformula/ 007 * 008 * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors. 009 * 010 * This library is free software; you can redistribute it and/or modify it under the terms 011 * of the GNU Lesser General Public License as published by the Free Software Foundation; 012 * either version 2.1 of the License, or (at your option) any later version. 013 * 014 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 015 * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 016 * See the GNU Lesser General Public License for more details. 017 * 018 * You should have received a copy of the GNU Lesser General Public License along with this 019 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, 020 * Boston, MA 02111-1307, USA. 021 * 022 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 023 * in the United States and other countries.] 024 * 025 * 026 * ------------ 027 * $Id: AverageFunction.java 3488 2007-10-10 09:48:59Z tmorgner $ 028 * ------------ 029 * (C) Copyright 2006-2007, by Pentaho Corporation. 030 */ 031 package org.jfree.formula.function.math; 032 033 import java.math.BigDecimal; 034 035 import org.jfree.formula.EvaluationException; 036 import org.jfree.formula.FormulaContext; 037 import org.jfree.formula.util.NumberUtil; 038 import org.jfree.formula.function.Function; 039 import org.jfree.formula.function.ParameterCallback; 040 import org.jfree.formula.lvalues.TypeValuePair; 041 import org.jfree.formula.typing.coretypes.NumberType; 042 043 /** 044 * This function returns the average of the number sequence. 045 * 046 * @author Cedric Pronzato 047 */ 048 public class AverageFunction implements Function 049 { 050 051 public AverageFunction() 052 { 053 } 054 055 public String getCanonicalName() 056 { 057 return "AVERAGE"; 058 } 059 060 public TypeValuePair evaluate(final FormulaContext context, 061 final ParameterCallback parameters) 062 throws EvaluationException 063 { 064 final SumFunction sumFunction = new SumFunction(); 065 final TypeValuePair sum = sumFunction.evaluate(context, parameters); 066 067 final Number n = context.getTypeRegistry().convertToNumber(sum.getType(), sum.getValue()); 068 final BigDecimal divident = NumberUtil.getAsBigDecimal(n); 069 final BigDecimal divisor = new BigDecimal(parameters.getParameterCount()); 070 final BigDecimal avg = divident.divide(divisor, 40, BigDecimal.ROUND_HALF_UP); 071 072 return new TypeValuePair(NumberType.GENERIC_NUMBER, avg); 073 } 074 }