DataFrame</span>
<span class="sd">    and returns the full dataset with log returns.</span>

<span class="sd">    :param df_full:              The time series</span>
<span class="sd">    :type  df_full:              pd.DataFrame</span>

<span class="sd">    :param lag:                  The lag between the series (in days)</span>
<span class="sd">    :type  lag:                  int</span>

<span class="sd">    :return:                     The DataFrame of time series with log returns</span>
<span class="sd"