Question

我正在尝试使用Caret软件包中的train()函数来拟合K最近邻居模型。这给我一个错误。我的代码是：

 "%+%" <- function(x,y) paste(x, y, sep = "")
 set.seed(28)
 ContEnt <- trainControl(method = "repeatedcv", number = 10, repeats = 3)
 EducKnn <- train(as.formula("pp04b_cod ~ " %+% paste(VarEduc[!VarEduc %in% NoRel], collapse 
                = " + ")), EducPrueba, method = "knn", trctrl = ContEnt,
               tuneLength = 10)

这给了我回报：

Warning: predictions failed for Resample01: k= 5 Error in knn3Train(train = structure(c(0.569069692629571, 0.569069692629571,  : 
  unused argument (trctrl = list("cv", 10, NA, "grid", 0.75, NULL, 1, TRUE, 0, FALSE, TRUE, "final", FALSE, FALSE, function (data, lev = NULL, model = NULL) 
{
    if (is.character(data$obs)) data$obs <- factor(data$obs, levels = lev)
    postResample(data[, "pred"], data[, "obs"])
}, "best", list(0.95, 3, 5, 19, 10, 0.9), NULL, NULL, NULL, NULL, 0, c(FALSE, FALSE), NA, list(5, 0.05, "gls", TRUE), FALSE, TRUE))

许多类似的警告信息，最后：

Warning in nominalTrainWorkflow(x = x, y = y, wts = weights, info = 
trainInfo,  :
There were missing values in resampled performance measures.
Something is wrong; all the Accuracy metric values are missing:          
    Accuracy       Kappa    
 Min.   : NA   Min.   : NA  
 1st Qu.: NA   1st Qu.: NA  
 Median : NA   Median : NA  
 Mean   :NaN   Mean   :NaN  
 3rd Qu.: NA   3rd Qu.: NA  
 Max.   : NA   Max.   : NA  
 NA's   :10    NA's   :10   
Error: Stopping
>

设置参数以避免交叉验证，似乎并不能解决问题。

ContEnt <- trainControl(method = "none")

此外，在train（）中设置na.action = na.omit也会得到相同的结果。有趣的是，该类程序包的knn（）函数在.75训练集上对相同的变量集可以完美地工作。

Entre <- createDataPartition(EducPrueba$pp04b_cod, 1, 0.75, list = FALSE)
EducKnn <- knn(train = EducPrueba[Entre, VarEduc[!VarEduc %in% NoRel]], test = EducPrueba[-Entre, 
VarEduc[!VarEduc %in% NoRel]], cl = EducPrueba$pp04b_cod[Entre], k = 5)

最后，可以肯定的是，EducPrueba没有NA或NaN：

> any(is.na(EducPrueba))
[1] FALSE
> any(unlist(lapply(EducPrueba, is.nan)))
[1] FALSE

VarEduc中的变量已经居中并缩放。有谁知道如何使它工作？我在RStudio中使用R Portable 3.5.2。包插入符6.0-81和7.3-15级。我不知道如何上传数据框，因此这可以是可重复的示例。

Answer 1

以下是重现错误的方法：

train(Species~.,data=iris,trctrl=trainControl(method="cv",numebr=5),
      metric="Accuracy",method="knn")
Something is wrong; all the Accuracy metric values are missing:
    Accuracy       Kappa    
 Min.   : NA   Min.   : NA  
 1st Qu.: NA   1st Qu.: NA  
 Median : NA   Median : NA  
 Mean   :NaN   Mean   :NaN  
 3rd Qu.: NA   3rd Qu.: NA  
 Max.   : NA   Max.   : NA  
 NA's   :3     NA's   :3    
>

错误：正在停止另外：有50个或更多警告（请使用warnings（）查看前50个警告）

以下是具有相同建议更改的相同型号：

train(Species~.,data=iris,trControl=trainControl(method="cv",number=5),
       metric="Accuracy",method="knn")
k-Nearest Neighbors 

150 samples
  4 predictor
  3 classes: 'setosa', 'versicolor', 'virginica' 

No pre-processing
Resampling: Cross-Validated (5 fold) 
Summary of sample sizes: 120, 120, 120, 120, 120 
Resampling results across tuning parameters:

解决您的问题 您需要将trctrl更改为trControl。

trainControl(method = "repeatedcv", number = 10, repeats = 3)
 EducKnn <- train(as.formula("pp04b_cod ~ " %+% paste(VarEduc[!VarEduc %in% NoRel], collapse 
                = " + ")), EducPrueba, method = "knn", trControl= ContEnt,
               tuneLength = 10)

使用Caret进行交叉验证重采样时缺少值

1 个答案: