&gt; Electricity [from Coal]             1          2                  3</span></span>
<span><span class="co">#&gt; Electricity [from Solar]            4          5                  6</span></span>
<span><span class="co">#&gt; attr(,"rowtype")</span></span>
<span><span class="co">#&gt; [1] "Product"</span></span>
<span><span class="co">#&gt; attr(,"coltype")</span></span>
<span><span class="co">#&gt; [1] "Industry"</span></span>
<span><span class="va">m_pieces_with_types</span> <span class="op"><a href="../