andidate neighbours. Because contiguity is symmetric, only i to
j contiguities are tested. A queen contiguity is found as soon as one
point matches, a rook contiguity as soon as two points match:</p>
<div class="sourceCode" id="cb6"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="fu"><a href="https://rdrr.io/r/base/message.html" class="external-link">suppressPackageStartupMessages</a></span><span class="op">(</span><span class="kw"><a href="https://rdrr.io/r/base/library.htm