我正在使用libsvm java包爲一個句子分類任務。我有3個班。每個句子都表示爲大小爲435的矢量。vector_file的格式如下:libsvm-java在幾次迭代訓練後拋出NullPointerException
1 0 0.12 0 0.5 0.24 0.32 0 0 0 ... 0.43 0
第一個數字表示類標籤,剩下的是矢量。
以下是我怎麼想提出的svm_problem:
public void makeSvmProb(ArrayList<Float> inputVector,float label,int p){
// p is 0 to 77 (total training sentences)
int idx=0,count=0;
svm_prob.y[p]=label;
for(int i=0;i<inputVector.size();i++){
if(inputVector.get(i)!=0) {
count++; // To get the count of non-zero values
}
}
svm_node[] x = new svm_node[count];
for(int i=0;i<inputVector.size();i++){
if(inputVector.get(i)!=0){
x[idx] = new svm_node();
x[idx].index = i;
x[idx].value = inputVector.get(i);
idx++;
}
}
svm_prob.x[p]=x;
}
參數設置:
param.svm_type = svm_parameter.C_SVC;
param.kernel_type = svm_parameter.RBF;
param.degree = 3;
param.gamma = 0.5;
param.coef0 = 0;
param.nu = 0.5;
param.cache_size = 40;
param.C = 1;
param.eps = 1e-3;
param.p = 0.1;
param.shrinking = 1;
param.probability = 0;
param.nr_weight = 0;
param.weight_label = new int[0];
param.weight = new double[0];
在執行程序時,經過2次迭代,我得到一個NullPointerException異常。我無法弄清楚發生了什麼問題。
這是錯誤來:
optimization finished, #iter = 85
nu = 0.07502654779820772
obj = -15.305162227093849, rho = -0.03157808477381625
nSV = 47, nBSV = 1
*
optimization finished, #iter = 88
nu = 0.08576821199868506
obj = -17.83925196551639, rho = 0.1297986754900152
nSV = 51, nBSV = 3
Exception in thread "main" java.lang.NullPointerException
at libsvm.Kernel.dot(svm.java:207)
at libsvm.Kernel.<init>(svm.java:199)
at libsvm.SVC_Q.<init>(svm.java:1156)
at libsvm.svm.solve_c_svc(svm.java:1333)
at libsvm.svm.svm_train_one(svm.java:1510)
at libsvm.svm.svm_train(svm.java:2067)
at SvmOp.<init>(SvmOp.java:130)
at Main.main(Main.java:8)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)
上什麼錯誤任何想法?
您是否嘗試設置斷點並在此上下文中調查究竟是否爲null? – rzo
@rzo ** svm_train **函數拋出異常。 – BBHeeMAA