title: Combing two objects of class ranger in R for survival analysis
body: <p>I am working on the R package <a href="https://cran.r-project.org/web/packages/ranger/index.html" rel="nofollow noreferrer">ranger</a> which is an implementation of random forest ensemble. I want to grow several sub forests and then combine them as one object to use for predicting new data. There is a <code>combine()</code> function within the <code>randomForest</code> R package but I want to do this for the <code>ranger</code> R package.
  An example of two sub forests could be</p>
  
  <pre><code>require(survival)
  require(ranger)
  rf1 &lt;- ranger(Surv(time, status) ~ ., data = veteran,num.tree=10)
  rf2 &lt;- ranger(Surv(time, status) ~ ., data = veteran,num.tree=10)
  
  rf &lt;- a function to combine rf1 and rf2.
  </code></pre>
  
  <p>I need such a function. Can anybody help?</p>