title: PCA analysis with triangular matrix
body: <p>I was trying to using PCA to analysis my data. But it ends like this:</p>
  <pre><code>&gt; head(MEGA)
  # A tibble: 6 × 86
    ...1    A2S10A16T18 K3N10E14 Q3H6G8K14 G4L8D14 W2G16Q17C18 H15K16 E3V9D10W14
    &lt;chr&gt;         &lt;dbl&gt;    &lt;dbl&gt;     &lt;dbl&gt;   &lt;dbl&gt;       &lt;dbl&gt;  &lt;dbl&gt;      &lt;dbl&gt;
  1 A2S10A…      NA       NA        NA      NA          NA         NA         NA
  2 K3N10E…       0.462   NA        NA      NA          NA         NA         NA
  3 Q3H6G8…       0.727    0.357    NA      NA          NA         NA         NA
  4 G4L8D14       0.583    0.357     0.357  NA          NA         NA         NA
  5 W2G16Q…       0.357    0.583     0.727   0.583      NA         NA         NA
  6 H15K16        0.357    0.357     0.462   0.357       0.357     NA         NA
  
  &gt; prcomp(MEGA)
  Error in colMeans(x, na.rm = TRUE) : 'x' must be numeric
  </code></pre>
  <p>Can you help me with this?</p>
  <p>I am freshman in bioinformation, thank you so much.</p>