R bnlearn内部函数评估 [英] R bnlearn eval inside function
本文介绍了R bnlearn内部函数评估的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在R中使用bnlearn包来训练贝叶斯网络.我对以下代码(稍作修改的bnlearn示例代码)感到烦恼:
I am using the bnlearn package in R to train a Bayesian network. I have troubles with the following code (slightly modified bnlearn example code):
library(bnlearn)
data(learning.test)
fitted = bn.fit(hc(learning.test), learning.test)
myfuncBN=function(){
var = names(learning.test)
obs = 2
str = paste("(", names(learning.test)[-3], "=='",
sapply(learning.test[obs,-3], as.character), "')",
sep = "", collapse = " & ")
str2 = paste("(", names(learning.test)[3], "=='",
as.character(learning.test[obs, 3]), "')", sep = "")
cpquery(fitted, eval(parse(text = str2)), eval(parse(text = str)))
}
myfuncBN()
此代码引发错误:
包装时出错:无法将类型'closure'强制转换为类型为'character'的向量
但是,如果在函数myfuncBN()之外定义了str和str2,则可以使用. 有人知道原因吗?
It works however if str and str2 are defined outside the function myfuncBN(). Does anyone know the reason for this?
推荐答案
以下是该问题的解决方案:
Here is a solution to the problem:
library(bnlearn)
data(learning.test)
fitted = bn.fit(hc(learning.test), learning.test)
myfuncBN=function() {
vars = names(learning.test)
obs = 2
str1 = paste("(", vars[-3], "=='",
sapply(learning.test[obs,-3], as.character), "')",
sep = "", collapse = " & ")
str2 = paste("(", vars[3], "=='",
as.character(learning.test[obs, 3]), "')", sep = "")
eval(parse(text=paste("cpquery(fitted,",str2,",",str1,")")))
}
set.seed(1)
myfuncBN()
# [1] 0.05940594
该值等于以下结果:
set.seed(1)
cpquery(fitted, event=(C=="c"),
evidence=((A=="b") & (B=="a") & (D=="a") & (E=="b") & (F=="b")))
# [1] 0.05940594
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