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1: /** 2: * ========================================= 3: * LibFormula : a free Java formula library 4: * ========================================= 5: * 6: * Project Info: http://reporting.pentaho.org/libformula/ 7: * 8: * (C) Copyright 2006-2007, by Pentaho Corporation and Contributors. 9: * 10: * This library is free software; you can redistribute it and/or modify it under the terms 11: * of the GNU Lesser General Public License as published by the Free Software Foundation; 12: * either version 2.1 of the License, or (at your option) any later version. 13: * 14: * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; 15: * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 16: * See the GNU Lesser General Public License for more details. 17: * 18: * You should have received a copy of the GNU Lesser General Public License along with this 19: * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, 20: * Boston, MA 02111-1307, USA. 21: * 22: * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 23: * in the United States and other countries.] 24: * 25: * 26: * ------------ 27: * $Id: AverageFunction.java,v 1.2 2007/05/08 09:47:09 taqua Exp $ 28: * ------------ 29: * (C) Copyright 2006-2007, by Pentaho Corporation. 30: */ 31: package org.jfree.formula.function.math; 32: 33: import java.math.BigDecimal; 34: 35: import org.jfree.formula.EvaluationException; 36: import org.jfree.formula.FormulaContext; 37: import org.jfree.formula.function.Function; 38: import org.jfree.formula.function.ParameterCallback; 39: import org.jfree.formula.lvalues.TypeValuePair; 40: import org.jfree.formula.typing.coretypes.NumberType; 41: 42: /** 43: * This function returns the average of the number sequence. 44: * 45: * @author Cedric Pronzato 46: */ 47: public class AverageFunction implements Function 48: { 49: 50: public AverageFunction() 51: { 52: } 53: 54: public String getCanonicalName() 55: { 56: return "AVERAGE"; 57: } 58: 59: public TypeValuePair evaluate(final FormulaContext context, 60: final ParameterCallback parameters) 61: throws EvaluationException 62: { 63: final SumFunction sumFunction = new SumFunction(); 64: final TypeValuePair sum = sumFunction.evaluate(context, parameters); 65: 66: final Number n = context.getTypeRegistry().convertToNumber(sum.getType(), sum.getValue()); 67: final BigDecimal divident = new BigDecimal(n.toString()); 68: final BigDecimal divisor = new BigDecimal(parameters.getParameterCount()); 69: final BigDecimal avg = divident.divide(divisor, BigDecimal.ROUND_HALF_UP); 70: 71: return new TypeValuePair(NumberType.GENERIC_NUMBER, avg); 72: } 73: }