R中的朴素贝叶斯无法预测-因子(0)水平:
我的数据集如下所示:R中的朴素贝叶斯无法预测-因子(0)水平:,r,machine-learning,bayesian,R,Machine Learning,Bayesian,我的数据集如下所示: 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
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
我试着按照naiveBayes中帮助手册中的示例进行操作,它对我很有用。我不确定我的方法有什么问题。非常感谢
我认为数据类型可能有问题,在应用naivebayes模型之前,我尝试使用
as.factor
将所有变量更改为factor,这似乎对我有用。但我仍然非常困惑幕后的“如何”和“为什么”是什么。问题不在于predict()
函数,而在于模型定义
naiveBayes()的帮助文件显示:
Computes the conditional a-posterior probabilities of a categorical class variable
given independent predictor variables using the Bayes rule.
所以y值应该是分类的,但在你的例子中它们是数字
解决方法是将flu
转换为因子
model <- naiveBayes(as.factor(flu)~., data=data.flu)
predict(model, patient)
[1] 1
Levels: 0 1
model嗯,非常感谢您的回答。我现在正在学习naiveBayes,模型与我的手工计算一致。我想知道predict
determinate y==1实际上如何具有更好的成本函数?成本函数在哪里?我如何在R中找到y=0和y=1的成本函数值?抱歉,我无法回答这个问题,因为我太熟悉naiveBayes了
model <- naiveBayes(as.factor(flu)~., data=data.flu)
predict(model, patient)
[1] 1
Levels: 0 1