我有一个数据集,看起来像这样:
data.flu <- data.frame(chills = c(1,1,1,0,0,0,0,1), runnyNose = c(0,1,0,1,0,1,1,1), headache = c("M", "N", "S", "M", "N", "S", "S", "M"), fever = c(1,0,1,1,0,1,0,1), flu = c(0,1,1,1,0,1,0,1) )
> data.flu
chills runnyNose headache fever flu
1 1 0 M 1 0
2 1 1 N 0 1
3 1 0 S 1 1
4 0 1 M 1 1
5 0 0 N 0 0
6 0 1 S 1 1
7 0 1 S 0 0
8 1 1 M 1 1
> str(data.flu)
'data.frame': 8 obs. of 5 variables:
$ chills : num 1 1 1 0 0 0 0 1
$ runnyNose: num 0 1 0 1 0 1 1 1
$ headache : Factor w/ 3 levels "M","N","S": 1 2 3 1 2 3 3 1
$ fever : num 1 0 1 1 0 1 0 1
$ flu : num 0 1 1 1 0 1 0 1
为什么
predict
函数没有返回任何值?# I can see the model has been successfully created.
model <- naiveBayes(flu~., data=data.flu)
# I created a new data
patient <- data.frame(chills = c(1), runnyNose = c(0), headache = c("M"), fever = c(1))
> predict(model, patient)
factor(0)
Levels:
# I tried with the training data, still won't work
> predict(model, data.flu[,-5])
factor(0)
Levels:
我尝试按照naiveBayes帮助手册中的示例操作,它对我有效。我不确定我的方法有什么问题。非常感谢!
我认为在应用naivebayes模型之前可能存在数据类型的问题,我尝试使用as.factor
将所有变量更改为因子,并且似乎对我有效。但是我仍然非常困惑背后的“如何”和“为什么”。
predict
是如何确定y==1实际上具有更好的代价函数?代价函数在哪里,我如何在R中找到y=0和y=1的代价函数值? - B.Mr.W.