ions on three variables</p><dl><dt>date</dt>
<dd><p>date when price was recorded</p></dd>

<dt>pricepergallon</dt>
<dd><p>price per gallon (in dollars)</p></dd>

<dt>location</dt>
<dd><p>a factor with levels <code>California</code>, <code>CentralAtlantic</code>,
<code>Coast</code>, <code>EastCoast</code>, <code>Gulf</code>, <code>LowerAtlantic</code>, <code>NatAvg</code>,
<code>NorthEast</code>, <code>Rocky</code>, and <code>WesternMountain</code></p></dd>


</dl></div>
    <div id="source">
    <h2>Source<