title: regarding data( ) function in R
body: <p>When using downloaded R packages, such as "tm", the given example usually loads an example data set such as</p>
  
  <pre><code>data("crude")
  </code></pre>
  
  <p>How can I know what exactly this data set is, and in which kind of format, a matrix or a vector?  Only by knowing this kind of information can I customize my input into the format required by this package. </p>