001 /*
002 * Copyright (c) 2005 Einar Pehrson <einar@pehrson.nu>.
003 *
004 * This file is part of
005 * CleanSheets - a spreadsheet application for the Java platform.
006 *
007 * CleanSheets is free software; you can redistribute it and/or modify
008 * it under the terms of the GNU General Public License as published by
009 * the Free Software Foundation; either version 2 of the License, or
010 * (at your option) any later version.
011 *
012 * CleanSheets is distributed in the hope that it will be useful,
013 * but WITHOUT ANY WARRANTY; without even the implied warranty of
014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
015 * GNU General Public License for more details.
016 *
017 * You should have received a copy of the GNU General Public License
018 * along with CleanSheets; if not, write to the Free Software
019 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020 */
021 package csheets.core.formula.lang;
022
023 import csheets.core.IllegalValueTypeException;
024 import csheets.core.Value;
025 import csheets.core.formula.Expression;
026 import csheets.core.formula.Function;
027 import csheets.core.formula.FunctionParameter;
028
029 /**
030 * A function that returns the numeric average of its arguments.
031 * @author Einar Pehrson
032 */
033 public class Average implements Function {
034
035 /** The only (but repeatable) parameter: a numeric term */
036 public static final FunctionParameter[] parameters = new FunctionParameter[] {
037 new FunctionParameter(Value.Type.NUMERIC, "Term", false,
038 "A number to be included in the average")
039 };
040
041 /**
042 * Creates a new instance of the AVERAGE function.
043 */
044 public Average() {}
045
046 public String getIdentifier() {
047 return "AVERAGE";
048 }
049
050 public Value applyTo(Expression[] arguments) throws IllegalValueTypeException {
051 double count = 0;
052 double sum = 0;
053 for (Expression expression : arguments) {
054 Value value = expression.evaluate();
055 if (value.getType() == Value.Type.NUMERIC) {
056 count++;
057 sum += value.toDouble();
058 } else if (value.getType() == Value.Type.MATRIX)
059 for (Value[] vector : value.toMatrix()) {
060 for (Value item : vector)
061 if (item.getType() == Value.Type.NUMERIC) {
062 count++;
063 sum += item.toDouble();
064 } else
065 throw new IllegalValueTypeException(item, Value.Type.NUMERIC);
066 } else
067 throw new IllegalValueTypeException(value, Value.Type.NUMERIC);
068 }
069 return new Value(sum / count);
070 }
071
072 public FunctionParameter[] getParameters() {
073 return parameters;
074 }
075
076 public boolean isVarArg() {
077 return true;
078 }
079 }