如何在使用confusionMatrix时解决错误

Question

我在使用confusionMatrix时收到错误但却失去了它的说法：

  

R：sort.list（y）出错：＆＃39; x＆＃39;必须是原子的

以下是我采取的步骤

# Cleaning the environment    
rm(list = ls())

# Reading the data
hr <- read.csv('C:/HR_comma_sep.csv')
    View(hr)

# load library randomForest
library(randomForest)

# Attaching the data    
attach(hr)
    head(hr)
    left <- as.data.frame(unlist(hr$left))
    set.seed(27)


rf <- randomForest(left~., data = hr, mtry = 4, ntree = 500, importance = T)
    plot(rf)
    varImpPlot(rf, sort = T, main = "Variable Importance", n.var = 5)
    hr$predicted.response <- predict(rf, left)
    library(lattice)
    library(ggplot2)
    library(caret)
    library(e1071)

# Confusion matrix for accuracy calculation
confusionMatrix(data = hr$predicted.response, reference = left,positive ='yes')