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我試圖調整pegasos算法參數，但沒有運氣。Pegasos參數調整
下面是使用6個一維點的簡單示例。
void dlib_svm_test()
{
for(double lambda= 10e-10;lambda<=10e10;lambda*=10)
{
typedef dlib::matrix<double, 0, 1> sample_type;
typedef dlib::linear_kernel<sample_type> kernel_type;
dlib::svm_pegasos<kernel_type> pegasos;
cout << lambda <<endl;
pegasos.set_lambda(lambda);
pegasos.set_kernel(kernel_type());
std::vector<sample_type> samples(6);
sample_type sample;
sample.set_size(1);
sample(0)= 188.0d;
samples[0]= sample;
sample(0)= 168.0d;
samples[1]= sample;
sample(0)= 191.0d;
samples[2]= sample;
sample(0)= 150.0d;
samples[3]= sample;
sample(0)= 154.0d;
samples[4]= sample;
sample(0)= 124.0d;
samples[5]= sample;
pegasos.train(samples[0],+1);
pegasos.train(samples[1],+1);
pegasos.train(samples[2],+1);
pegasos.train(samples[3],-1);
pegasos.train(samples[4],-1);
pegasos.train(samples[5],-1);
cout<< pegasos(samples[0]) <<endl;
cout<< pegasos(samples[1]) <<endl;
cout<< pegasos(samples[2]) <<endl;
cout<< pegasos(samples[3]) <<endl;
cout<< pegasos(samples[4]) <<endl;
cout<< pegasos(samples[5]) <<endl;
pegasos.clear();
}
}
，我得到的輸出：
0.0000000010
-3963387.1199921928
-3541750.1923335334
-4026632.6591409920
-3162276.9574407390
-3246604.3429724714
-2614148.9514844813
0.0000000100
-1253333.0548153266
-1119999.7511116527
-1273333.0503708781
-999999.7777783460
-1026666.4385190808
-826666.4829635697
0.0000001000
-396338.7119995961
-354175.0192337657
-402663.2659144707
-316227.6957445183
-324660.4342976844
-261414.8951489388
0.0000010000
-125333.3054819095
-111999.9751115777
-127333.3050374593
-99999.9777782790
-102666.6438523454
-82666.6482968476
0.0000100000
-39633.8712003365
-35417.5019237890
-40266.3265918186
-31622.7695748963
-32466.0434302058
-26141.4895153846
0.0001000000
-12533.3305485679
-11199.9975115703
-12733.3305041176
-9999.9977782724
-10266.6643856720
-8266.6648301755
0.0010000000
-3963.3871204108
-3541.7501927916
-4026.6326595536
-3162.2769579343
-3246.6043434582
-2614.1489520294
0.0100000000
-1253.3330552344
-1119.9997515702
-1273.3330507840
-999.9997782725
-1026.6664390053
-826.6664835091
0.1000000000
-396.3387124203
-354.1750196940
-402.6632663292
-316.2276962404
-324.6604347856
-261.4148956963
1.0000000000
-125.3333059077
-111.9999755772
-127.3333054573
-99.9999782797
-102.6666443458
-82.6666488500
10.0000000000
-39.6338716427
-35.4175024067
-40.2663270281
-31.6227700943
-32.4660439415
-26.1414900875
100.0000000000
-12.5333310483
-11.1999980544
-12.7333309973
-9.9999983600
-10.2666649587
-8.2666654680
1000.0000000000
-3.7091542406
-3.3145634810
-3.7683428546
-2.9594317974
-3.0383499493
-2.4464638100
10000.0000000000
-0.4292670207
-0.3836003494
-0.4361170215
-0.3425003451
-0.3516336794
-0.2831336723
100000.0000000000
0.0372866667
0.0333200000
0.0378816667
0.0297500000
0.0305433333
0.0245933333
1000000.0000000000
0.0037286667
0.0033320000
0.0037881667
0.0029750000
0.0030543333
0.0024593333
10000000.0000000000
0.0003728667
0.0003332000
0.0003788167
0.0002975000
0.0003054333
0.0002459333
100000000.0000000000
0.0000372867
0.0000333200
0.0000378817
0.0000297500
0.0000305433
0.0000245933
1000000000.0000000000
0.0000037287
0.0000033320
0.0000037882
0.0000029750
0.0000030543
0.0000024593
10000000000.0000000000
0.0000003729
0.0000003332
0.0000003788
0.0000002975
0.0000003054
0.0000002459
100000000000.0000000000
0.0000000373
0.0000000333
0.0000000379
0.0000000297
0.0000000305
0.0000000246
所以我得到的問題，所有樣品預測爲陰性或陽性。
UPDATE：
問題解決了：
https://github.com/davisking/dlib/issues/49
