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    <p>You want the <code>$loadings</code> component of the returned object:</p> <pre><code>R&gt; class(pca$loadings) [1] "loadings" R&gt; pca$loadings Loadings: Comp.1 Comp.2 Comp.3 Comp.4 Comp.5 a -0.198 0.713 -0.671 b 0.600 0.334 -0.170 0.707 c -0.600 -0.334 0.170 0.707 d 0.439 -0.880 -0.180 e 0.221 0.701 0.678 Comp.1 Comp.2 Comp.3 Comp.4 Comp.5 SS loadings 1.0 1.0 1.0 1.0 1.0 Proportion Var 0.2 0.2 0.2 0.2 0.2 Cumulative Var 0.2 0.4 0.6 0.8 1.0 </code></pre> <p>Note that this has a special <code>print()</code> method which suppresses <em>printing</em> of small loadings.</p> <p>If you want this as a relative contribution then sum up the loadings per column and express each loading as a proportion of the column (loading) sum, taking care to use the absolute values to account for negative loadings.</p> <pre><code>R&gt; load &lt;- with(pca, unclass(loadings)) R&gt; load Comp.1 Comp.2 Comp.3 Comp.4 Comp.5 a -0.1980087 0.712680378 0.04606100 -0.6713848 0.000000e+00 b 0.5997346 -0.014945831 0.33353047 -0.1698602 7.071068e-01 c -0.5997346 0.014945831 -0.33353047 0.1698602 7.071068e-01 d 0.4389388 0.009625746 -0.88032515 -0.1796321 5.273559e-16 e 0.2208215 0.701104321 -0.02051507 0.6776944 -1.110223e-16 </code></pre> <p>This final step then yields the proportional contribution to the each principal component</p> <pre><code>R&gt; aload &lt;- abs(load) ## save absolute values R&gt; sweep(aload, 2, colSums(aload), "/") Comp.1 Comp.2 Comp.3 Comp.4 Comp.5 a 0.09624979 0.490386943 0.02853908 0.35933068 0.000000e+00 b 0.29152414 0.010284050 0.20665322 0.09091055 5.000000e-01 c 0.29152414 0.010284050 0.20665322 0.09091055 5.000000e-01 d 0.21336314 0.006623362 0.54544349 0.09614059 3.728970e-16 e 0.10733880 0.482421595 0.01271100 0.36270762 7.850462e-17 R&gt; colSums(sweep(aload, 2, colSums(aload), "/")) Comp.1 Comp.2 Comp.3 Comp.4 Comp.5 1 1 1 1 1 </code></pre> <hr> <p>If using the preferred <code>prcomp()</code> then the relevant loadings are in the <code>$rotation</code> component:</p> <pre><code>R&gt; pca2 &lt;- prcomp(my_table, scale = TRUE) R&gt; pca2$rotation PC1 PC2 PC3 PC4 PC5 a -0.1980087 0.712680378 -0.04606100 -0.6713848 0.000000e+00 b 0.5997346 -0.014945831 -0.33353047 -0.1698602 -7.071068e-01 c -0.5997346 0.014945831 0.33353047 0.1698602 -7.071068e-01 d 0.4389388 0.009625746 0.88032515 -0.1796321 -3.386180e-15 e 0.2208215 0.701104321 0.02051507 0.6776944 5.551115e-17 </code></pre> <p>And the relevant incantation is now:</p> <pre><code>R&gt; aload &lt;- abs(pca2$rotation) R&gt; sweep(aload, 2, colSums(aload), "/") PC1 PC2 PC3 PC4 PC5 a 0.09624979 0.490386943 0.02853908 0.35933068 0.000000e+00 b 0.29152414 0.010284050 0.20665322 0.09091055 5.000000e-01 c 0.29152414 0.010284050 0.20665322 0.09091055 5.000000e-01 d 0.21336314 0.006623362 0.54544349 0.09614059 2.394391e-15 e 0.10733880 0.482421595 0.01271100 0.36270762 3.925231e-17 </code></pre>
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    1. COExactly what I was looking for! Thank you very much (it actually let me say an American "awesome"!).
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