tion level1">
<h1></h1>
<p>So far we have seen a whole lot in <code>j</code>, and how to combine it with <code>by</code> and little of <code>i</code>. Let’s turn our attention back to <code>i</code> in the next vignette <em>“Keys and fast binary search based subset”</em> to perform <em>blazing fast subsets</em> by <em>keying data.tables</em>.</p>
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