ConfusionMatrix 中的误差数据和参考因子必须具有相同的级别数

Question

I've trained a tree model with R caret. I'm now trying to generate a confusion matrix and keep getting the following error:

Error in confusionMatrix.default(predictionsTree, testdata$catgeory) : the data and reference factors must have the same number of levels

prob <- 0.5 #Specify class split
singleSplit <- createDataPartition(modellingData2$category, p=prob,
                                   times=1, list=FALSE)
cvControl <- trainControl(method="repeatedcv", number=10, repeats=5)
traindata <- modellingData2[singleSplit,]
testdata <- modellingData2[-singleSplit,]
treeFit <- train(traindata$category~., data=traindata,
                 trControl=cvControl, method="rpart", tuneLength=10)
predictionsTree <- predict(treeFit, testdata)
confusionMatrix(predictionsTree, testdata$catgeory)

The error occurs when generating the confusion matrix. The levels are the same on both objects. I cant figure out what the problem is. Their structure and levels are given below. They should be the same. Any help would be greatly appreciated as its making me cracked!!

> str(predictionsTree)
 Factor w/ 30 levels "16-Merchant Service Charge",..: 28 22 22 22 22 6 6 6 6 6 ...
> str(testdata$category)
 Factor w/ 30 levels "16-Merchant Service Charge",..: 30 30 7 7 7 7 7 30 7 7 ...

> levels(predictionsTree)
 [1] "16-Merchant Service Charge"   "17-Unpaid Cheque Fee"         "18-Gov. Stamp Duty"           "Misc"                         "26-Standard Transfer Charge" 
 [6] "29-Bank Giro Credit"          "3-Cheques Debit"              "32-Standing Order - Debit"    "33-Inter Branch Payment"      "34-International"            
[11] "35-Point of Sale"             "39-Direct Debits Received"    "4-Notified Bank Fees"         "40-Cash Lodged"               "42-International Receipts"   
[16] "46-Direct Debits Paid"        "56-Credit Card Receipts"      "57-Inter Branch"              "58-Unpaid Items"              "59-Inter Company Transfers"  
[21] "6-Notified Interest Credited" "61-Domestic"                  "64-Charge Refund"             "66-Inter Company Transfers"   "67-Suppliers"                
[26] "68-Payroll"                   "69-Domestic"                  "73-Credit Card Payments"      "82-CHAPS Fee"                 "Uncategorised"   

> levels(testdata$category)
 [1] "16-Merchant Service Charge"   "17-Unpaid Cheque Fee"         "18-Gov. Stamp Duty"           "Misc"                         "26-Standard Transfer Charge" 
 [6] "29-Bank Giro Credit"          "3-Cheques Debit"              "32-Standing Order - Debit"    "33-Inter Branch Payment"      "34-International"            
[11] "35-Point of Sale"             "39-Direct Debits Received"    "4-Notified Bank Fees"         "40-Cash Lodged"               "42-International Receipts"   
[16] "46-Direct Debits Paid"        "56-Credit Card Receipts"      "57-Inter Branch"              "58-Unpaid Items"              "59-Inter Company Transfers"  
[21] "6-Notified Interest Credited" "61-Domestic"                  "64-Charge Refund"             "66-Inter Company Transfers"   "67-Suppliers"                
[26] "68-Payroll"                   "69-Domestic"                  "73-Credit Card Payments"      "82-CHAPS Fee"                 "Uncategorised"       

Answer 1

Try use:

confusionMatrix(table(Argument 1, Argument 2)) 

Thats worked for me.

Answer 2

Maybe your model is not predicting a certain factor. Use the table() function instead of confusionMatrix() to see if that is the problem.

Answer 3

尝试为na.action选项指定na.pass ：

predictionsTree <- predict(treeFit, testdata,na.action = na.pass)

Answer 4

Change them into a data frame and then use them in confusionMatrix function:

pridicted <- factor(predict(treeFit, testdata))
real <- factor(testdata$catgeory)

my_data1 <- data.frame(data = pridicted, type = "prediction")
my_data2 <- data.frame(data = real, type = "real")
my_data3 <- rbind(my_data1,my_data2)

# Check if the levels are identical
identical(levels(my_data3[my_data3$type == "prediction",1]) , levels(my_data3[my_data3$type == "real",1]))

confusionMatrix(my_data3[my_data3$type == "prediction",1], my_data3[my_data3$type == "real",1],  dnn = c("Prediction", "Reference"))

Answer 5

Might be there are missing values in the testdata, Add the following line before "predictionsTree <- predict(treeFit, testdata)" to remove NAs. I had the same error and now it works for me.

testdata <- testdata[complete.cases(testdata),]

Answer 6

您遇到的长度问题可能是由于训练集中存在 NAs - 要么删除不完整的案例，要么进行估算以使您没有缺失值。

Answer 7

I had same issue but went ahead and changed it after reading data file like so..

data = na.omit(data)

Thanks all for pointer!

Answer 8

make sure you installed the package with all its dependencies:

install.packages('caret', dependencies = TRUE)

confusionMatrix( table(prediction, true_value) )

Answer 9

If your data contains NAs then sometimes it will be considered as a factor level,So omit these NAs initially

DF = na.omit(DF)

Then,if your model fit is predicting some incorrect level,then it is better to use tables

confusionMatrix(table(Arg1, Arg2))

Answer 10

I just ran into the same problem, I solved it by using R ordered factor data type.

levels <- levels(predictionsTree)
levels <- levels[order(levels)]    
table(ordered(predictionsTree,levels), ordered(testdata$catgeory, levels))