pan><span class="n">data_df</span><span class="p">[</span><span class="n">numeric_columns</span><span class="p">]</span><span class="o">.</span><span class="n">mean</span><span class="p">())</span>

    <span class="c1"># Fill NaN in non-numeric columns with &#39;Unknown&#39;</span>
    <span class="n">data_df</span><span class="p">[</span><span class="n">non_numeric_columns</span><span class="p">]</span> <span class="o">=</span> <span class="n">data_df</span><span class="p">[</span><span class="n">non_nume