R bnlearn eval inside a function
I am using the bnlearn package in R to train a Bayesian network. I'm having trouble 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()
This code throws an error:
Wrapping error: cannot force type "close" to a vector of type "character"
It works, however, if str and str2 are defined outside of the myfuncBN () function. Does anyone know the reason for this?
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1 answer
Here is the 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
This value is equal to the result:
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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