title: Pass PCA preprocessing arguments to train()
body: <p>I'm trying to build a predictive model in caret using PCA as pre-processing. The pre-processing would be as follows:</p>
  
  <pre><code>preProc &lt;- preProcess(IL_train[,-1], method="pca", thresh = 0.8)
  </code></pre>
  
  <p>Is it possible to pass the <code>thresh</code> argument directly to caret's <code>train()</code> function? I've tried the following, but it doesn't work:</p>
  
  <pre><code>modelFit_pp &lt;- train(IL_train$diagnosis ~ . , preProcess="pca",
                              thresh= 0.8, method="glm", data=IL_train)
  </code></pre>
  
  <p>If not, how can I pass the separate <code>preProc</code> results to the <code>train()</code> function?</p>