从R中的e1071包训练SVM时获得错误"(下标)逻辑下标太长"

Question

我正在使用我的traindata训练svm.(E1071包装在R中).以下是有关我的数据的信息.

> str(train)
'data.frame':   891 obs. of  10 variables:
$ survived: int  0 1 1 1 0 0 0 0 1 1 ...
$ pclass  : int  3 1 3 1 3 3 1 3 3 2 ...
$ name    : Factor w/ 15 levels "capt","col","countess",..: 12 13 9 13 12 12 12 8 13 13 
$ sex     : Factor w/ 2 levels "female","male": 2 1 1 1 2 2 2 2 1 1 ...
$ age     : num  22 38 26 35 35 ...
$ ticket  : Factor w/ 533 levels "110152","110413",..: 516 522 531 50 473 276 86 396 
$ fare    : num  7.25 71.28 7.92 53.1 8.05 ...
$ cabin   : Factor w/ 9 levels "a","b","c","d",..: 9 3 9 3 9 9 5 9 9 9 ...
$ embarked: Factor w/ 4 levels "","C","Q","S": 4 2 4 4 4 3 4 4 4 2 ...
$ family  : int  1 1 0 1 0 0 0 4 2 1 ...

我训练如下.

library(e1071)
model1 <- svm(survived~.,data=train, type="C-classification")

这里没问题.但是当我预测为:

pred <- predict(model1,test)

我收到以下错误:

Error in newdata[, object$scaled, drop = FALSE] : 
(subscript) logical subscript too long

我还尝试从列车和测试数据中删除"票证"预测器.但仍然是同样的错误.问题是什么？

Answer 1

"测试"数据集中某个因素的级别数可能存在差异.

运行str(test)并检查因子变量与'train'数据集中的对应变量具有相同的级别.

即下面的例子显示my.test $ foo只有4个级别.....

str(my.train)
'data.frame':   554 obs. of  7 variables:
 ....
 $ foo: Factor w/ 5 levels "C","Q","S","X","Z": 2 2 4 3 4 4 4 4 4 4 ...

str(my.test)
'data.frame':   200 obs. of  7 variables:
 ...
 $ foo: Factor w/ 4 levels "C","Q","S","X": 3 3 3 3 1 3 3 3 3 3 ...