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MATLAB聚类有效性评价指标（外部 成对度量）
作者：凯鲁嘎吉 - 博客园 http://www.cnblogs.com/kailugaji/
更多内容，请看：MATLAB: Clustering Algorithms， MATLAB聚类有效性评价指标（外部）
前提：数据的真实标签已知！TP：真阳性，FP：假阳性，FN：假阴性，TN：真阴性
1. MATLAB程序
function result = Evaluate(real_label,pre_label)
% This fucntion evaluates the performance of a classification model by
% calculating the common performance measures: Accuracy, Sensitivity,
% Specificity, Precision, Recall, F-Measure, G-mean.
% Input: ACTUAL = Column matrix with actual class labels of the training
% examples
% PREDICTED = Column matrix with predicted class labels by the
% classification model
% Output: EVAL = Row matrix with all the performance measures
% https://www.mathworks.com/matlabcentral/fileexchange/37758-performance-measures-for-classification
idx = (real_label()==1);
p = length(real_label(idx));
n = length(real_label(~idx));
N = p+n;
tp = sum(real_label(idx)==pre_label(idx));
tn = sum(real_label(~idx)==pre_label(~idx));
fp = n-tn;
fn = p-tp;
tp_rate = tp/p;
tn_rate = tn/n;
accuracy = (tp+tn)/N; %准确度
sensitivity = tp_rate; %敏感性：真阳性率
specificity = tn_rate; %特异性：真阴性率
precision = tp/(tp+fp); %精度
recall = sensitivity; %召回率
f_measure = 2*((precision*recall)/(precision + recall)); %F-measure
gmean = sqrt(tp_rate*tn_rate);
Jaccard=tp/(tp+fn+fp); %Jaccard系数
result = [accuracy sensitivity specificity precision recall f_measure gmean Jaccard];
fprintf('accuracy=%.4f, sensitivity=%.4f, specificity=%.4f, precision=%.4f, recall=%.4f, f_measure=%.4f, gmean=%.4f, Jaccard=%.4f\n', ...
accuracy, sensitivity, specificity, precision, recall, f_measure, gmean, Jaccard);
2. 结果
>> A = [1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3];
>> B = [1 2 1 1 1 1 1 2 2 2 2 3 1 1 3 3 3];
>> result = Evaluate(A,B)
accuracy=0.7059, sensitivity=0.8333, specificity=0.6364, precision=0.5556, recall=0.8333, f_measure=0.6667, gmean=0.7282, Jaccard=0.5000
result =
0.705882352941177 0.833333333333333 0.636363636363636 0.555555555555556 0.833333333333333 0.666666666666667 0.728219081254419 0.500000000000000
3. 参考
[1] MATLAB聚类有效性评价指标（外部）
[2] 相似性度量
[3] Performance Measures for Classification
[4] Gaussian field consensus论文解读及MATLAB实现
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