I am trying to replicate a example that I found on Tom Mitchell's Machine Learning book using R. It is a example from chapter 6. There are 14 training examples (shown bellow) of the target concept PlayTennis, where each day is described by the attributes Outlook, Temperature, Humidity, and Windy.
Training examples
Outlook,Temperature,Humidity,Windy,Play
overcast,cool,normal,true,yes
overcast,hot,high,false,yes
overcast,hot,normal,false,yes
overcast,mild,high,true,yes
rainy,cool,normal,false,yes
rainy,mild,high,false,yes
rainy,mild,normal,false,yes
sunny,cool,normal,false,yes
sunny,mild,normal,true,yes
rainy,cool,normal,true,no
rainy,mild,high,true,no
sunny,hot,high,false,no
sunny,hot,high,true,no
sunny,mild,high,false,no
Here's my code
library("klaR")
library("caret")
data = read.csv("example.csv")
x = data[,-5]
y = data$Play
model = train(x,y,'nb',trControl=trainControl(method='cv',number=10))
Outlook <- "sunny"
Temperature <- "cool"
Humidity <- "high"
Windy <- "true"
instance <- data.frame(Outlook,Temperature,Humidity,Windy)
predict(model$finalModel,instance)
The example tries to predict the outcome for
Outlook=sunny, Temperature=cool,Humidity=high and Wind=strong
The problem is that I am getting a different prediction from the one in the book.
Here's the probabilities I've got from my code
no yes
0.001078835 0.9989212
Here's the book's probabilities
no yes
0.0206 0.0053
My code classifies the unseen data as Yes and the book's classifier classifies it as No.
Shouldn't both give the same answer since we are using the same naive bayes classifier?