SVM从测试数据预测中抛出NA

Question

我正在使用机器学习的SVM方法。当我使用模型对测试数据集进行预测时，我得到了所有NA。我认为问题出在kernlab。我该如何处理？任何建议将不胜感激。谢谢

library(e1071)

library(kernlab)

model_svm<-train(nzv[index,], trainSet.y, method='svmRadial', trControl=fitControl, tuneLength=6)

testSet$model_svm <- predict(model_svm, testSet)

testSet$model_svm <- predict(model_svm, testSet) Warning message: In method$predict(modelFit = modelFit, newdata = newdata, submodels = param) : kernlab class prediction calculations failed; returning NAs

  

testSet $ model_svm    [1]   [25]   级别：N Y