>_rng</code> because it uses other random functions internally. This will restrict its usage to the transformed data and generated quantities block. The code walks through an array of integers exchanging each item with another randomly chosen item, resulting in a uniformly drawn permutation of the integers <code>1:N</code>.<a href="#fn1" class="footnote-ref" id="fnref1" role="doc-noteref"><sup>1</sup></a></p>
<p>The transformed data block uses the permutation RNG to generate training data and test data by t