</code></pre>
<pre><code>The following object is masked from &#39;package:stats&#39;:

    step</code></pre>
<pre class="r"><code>library(pROC)</code></pre>
<pre><code>Type &#39;citation(&quot;pROC&quot;)&#39; for a citation.</code></pre>
<pre><code>
Attaching package: &#39;pROC&#39;</code></pre>
<pre><code>The following objects are masked from &#39;package:stats&#39;:

    cov, smooth, var</code></pre>
<pre class="r"><code>library(gbm)</code></pre>
<pre><code>Loaded gbm 2.1.8</code></pre>
<pre class="r"><c