/*******************************************************************************
* Copyright (c) 2010 Haifeng Li
*
* 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.
*******************************************************************************/
package smile.validation;
/**
* Fall-out, false alarm rate, or false positive rate (FPR)
* <p>
* FPR = FP / N = FP / (FP + TN)
* <p>
* Fall-out is actually Type I error and closely related to specificity
* (1 - specificity).
*
* @author Haifeng Li
*/
public class Fallout implements ClassificationMeasure {
@Override
public double measure(int[] truth, int[] prediction) {
if (truth.length != prediction.length) {
throw new IllegalArgumentException(String.format("The vector sizes don't match: %d != %d.", truth.length, prediction.length));
}
int tn = 0;
int n = 0;
for (int i = 0; i < truth.length; i++) {
if (truth[i] != 1) {
n++;
if (prediction[i] == truth[i]) {
tn++;
}
}
}
return 1.0 - (double) tn / n;
}
@Override
public String toString() {
return "Fall-out";
}
}