/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.mahout.classifier.df;
import com.google.common.base.Preconditions;
/**
* Various methods to compute from the output of a random forest
*/
public final class ErrorEstimate {
private ErrorEstimate() {
}
public static double errorRate(double[] labels, double[] predictions) {
Preconditions.checkArgument(labels.length == predictions.length, "labels.length != predictions.length");
double nberrors = 0; // number of instance that got bad predictions
double datasize = 0; // number of classified instances
for (int index = 0; index < labels.length; index++) {
if (predictions[index] == -1) {
continue; // instance not classified
}
if (predictions[index] != labels[index]) {
nberrors++;
}
datasize++;
}
return nberrors / datasize;
}
}