"The format of predictions is incorrect" - r

Question

Implementation of ROCR curve, kNN ,K 10 fold cross validation.
I am using Ionosphere dataset.
Here is the attribute information for your reference:
-- All 34 are continuous, as described above
-- The 35th attribute is either "good" or "bad" according to the definition
summarized above. This is a binary classification task.
data1<-read.csv('https://archive.ics.uci.edu/ml/machine-learning-databases/ionosphere/ionosphere.data',header = FALSE)
knn on its own works, kNN with kfold also works. But when I put in the ROCR code it doesnt like it.
I get the error: "The format of predictions is incorrect".
I checked the dataframes pred and Class 1. The dimensions are same. I tried with data.test$V35 instead of Class1 I get the same error with this option.
install.packages("class")
library(class)
nrFolds <- 10
data1[,35]<-as.numeric(data1[,35])
# generate array containing fold-number for each sample (row)
folds <- rep_len(1:nrFolds, nrow(data1))
# actual cross validation
for(k in 1:nrFolds) {
# actual split of the data
fold <- which(folds == k)
data.train <- data1[-fold,]
data.test <- data1[fold,]
Class<-data.train[,35]
Class1<-data.test[,35]
# train and test your model with data.train and data.test
pred<-knn(data.train, data.test, Class, k = 5, l = 0, prob = FALSE, use.all = TRUE)
data<-data.frame('predict'=pred, 'actual'=Class1)
count<-nrow(data[data$predict==data$actual,])
total<-nrow(data.test)
avg = (count*100)/total
avg =format(round(avg, 2), nsmall = 2)
method<-"KNN"
accuracy<-avg
cat("Method = ", method,", accuracy= ", accuracy,"\n")
}
install.packages("ROCR")
library(ROCR)
rocrPred=prediction(pred, Class1, NULL)
rocrPerf=performance(rocrPred, 'tpr', 'fpr')
plot(rocrPerf, colorize=TRUE, text.adj=c(-.2,1.7))
Any help is appreciated.

Answer 1

This worked for me..
install.packages("class")
library(class)
library(ROCR)
nrFolds <- 10
data1[,35]<-as.numeric(data1[,35])
# generate array containing fold-number for each sample (row)
folds <- rep_len(1:nrFolds, nrow(data1))
# actual cross validation
for(k in 1:nrFolds) {
# actual split of the data
fold <- which(folds == k)
data.train <- data1[-fold,]
data.test <- data1[fold,]
Class<-data.train[,35]
Class1<-data.test[,35]
# train and test your model with data.train and data.test
pred<-knn(data.train, data.test, Class, k = 5, l = 0, prob = FALSE, use.all = TRUE)
data<-data.frame('predict'=pred, 'actual'=Class1)
count<-nrow(data[data$predict==data$actual,])
total<-nrow(data.test)
avg = (count*100)/total
avg =format(round(avg, 2), nsmall = 2)
method<-"KNN"
accuracy<-avg
cat("Method = ", method,", accuracy= ", accuracy,"\n")
pred <- prediction(Class1,pred)
perf <- performance(pred, "tpr", "fpr")
plot(perf, colorize=T, add=TRUE)
abline(0,1)
}