n></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="va">real_map</span> <span class="op">&lt;-</span> <span class="fu">world</span><span class="op">(</span>xrange <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="op">-</span><span class="fl">15</span>, <span class="fl">40</span><span class="op">)</span>, yrange <span class="op">=</span> <span class="fu"><a href=