_df</span><span class="op">)</span></span></code></pre></div>
    </div>

    <div id="arguments">
    <h2>Arguments</h2>
    <dl><dt>df</dt>
<dd><p>A data source before preprocessing, that is one of the major R formats:
data.table, data.frame, matrix, and so on.</p></dd>


<dt>pre_df</dt>
<dd><p>A data source after preprocessing, that is one of the major R formats:
data.table, data.frame, matrix, and so on.</p></dd>

</dl></div>
    <div id="value">
    <h2>Value</h2>
    

<p>A vector o