nput data</span>
<span class="n">dem_path</span> <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;DEM_TX.tif&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">shape_path</span> <