title: Find index of the last occurence for maximal value in pd.DataFrame
body: <p>I need to find <code>argmax</code> index in pd.DataFrame. I want exacly the same result, as <code>pandas.DataFrame.idxmax</code> does, but this function returns index of <strong>first</strong> occurrence of maximum over requested axis. I want find index of <strong>last</strong> occurrence of maximum. Thank you in advance.</p>