"><a href="https://tidyr.tidyverse.org/reference/gather.html" class="external-link">gather</a></span><span class="op">(</span>key <span class="op">=</span> <span class="va">Year</span>, value <span class="op">=</span> <span class="va">matrix</span>, <span class="va">`2000`</span>, <span class="va">`2001`</span><span class="op">)</span> <span class="op"><a href="../reference/pipe.html">%&gt;%</a></span> </span>
<span>  <span class="co"># Now spread to put each matrix in a column.</span></span>
<span>  <span 