title: Rpart split error: Agument split not matched
body: <p>I want to change the splitting method in <code>rpart</code> function from "gini" (which is default) to "information".</p>
  
  <p>In the help section we have this example:</p>
  
  <pre><code>fit2 &lt;- rpart(Kyphosis ~ Age + Number + Start, data = kyphosis,
                parms = list(prior = c(.65,.35), split = "information"))
  </code></pre>
  
  <p>in <code>method</code> argument details we have:
  "Alternatively, method can be a list of functions named init, split and eval. Examples are given in the file ‘tests/usersplits.R’ in the sources, and in the vignettes ‘User Written Split Functions"</p>
  
  <p>and in the <code>parms</code> argument details:
  "The splitting index can be gini or information. The default priors are proportional to the data counts, the losses default to 1, and the split defaults to gini."</p>
  
  <p>When I try to create the model:</p>
  
  <pre><code>model&lt;-rpart(as.factor(char)~., data=train, split = "information")
  Error: ***Argument split not matched***
  </code></pre>
  
  <p>I find this (and most of the) R help sections not very clear. 
  Apparently I do not have the <em>information</em> option. Am I supposed to define the function for split before and then build my model?, or also input the probabilities vector? How can I use <em>information</em> like in the example? </p>