span class="o">&lt;-</span> <span class="n">system</span><span class="o">.</span><span class="n">file</span><span class="p">(</span><span class="s2">&quot;extdata&quot;</span><span class="p">,</span>
                <span class="s2">&quot;basin.shp&quot;</span><span class="p">,</span>
                <span class="n">package</span> <span class="o">=</span> <span class="s2">&quot;NASAaccess&quot;</span><span class="p">)</span>


 <span class="n">dem</span> <span class="o">&lt;-</span> <span class="n">raster</