| package com.yahoo.labs.samoa.moa.classifiers.core.splitcriteria; |
| |
| /* |
| * #%L |
| * SAMOA |
| * %% |
| * Copyright (C) 2012 University of Waikato, Hamilton, New Zealand |
| * %% |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * #L% |
| */ |
| |
| public class SDRSplitCriterion extends VarianceReductionSplitCriterion { |
| private static final long serialVersionUID = 1L; |
| |
| public static double computeSD(double[] dist) { |
| int N = (int) dist[0]; |
| double sum = dist[1]; |
| double sumSq = dist[2]; |
| return Math.sqrt((sumSq - ((sum * sum) / N)) / N); |
| } |
| |
| } |