CODEWITHSUNDEEP
r
Ankita
Ankita

Reputation: 2868

How predict function works

Iam using this command in R for building decision trees :

> library(party) 
> ind = sample(2,nrow(iris),replace=TRUE,prob=c(0.8,0.2))
> myFormula <- Species ~ Sepal.Length + Sepal.Width + Petal.Length + Petal.Width
> iris_ctree <- ctree(myFormula,data = iris[ind==1,])
> predict(iris_ctree)

What exactly does predict function compute and how does it perform the computation?

Upvotes: 1

Views: 4075

Answers (1)

Aditya Sihag
Aditya Sihag

Reputation: 5167

the example first constructs "ind" based on a sampling of 1's with probability .8 and 2's with probability .2. It then specifies a Formula that defines the hypothesis function for the model. It then fits the conditional inference tree to the estimate the parameters based on the hypothesis specification using the sampled data - which is just the data containing 1's.

It then runs a prediction based on the full sample of 1's and 2's.

So basically it trained on 1's, but runs predict on 1's and 2's.

Upvotes: 1

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