pandas.DataFrame.idxmax

DataFrame.idxmax(axis=0, skipna=True)

Return index of first occurrence of maximum over requested axis. NA/null values are excluded.

axis : {0, 1}
0 for row-wise, 1 for column-wise
skipna : boolean, default True
Exclude NA/null values. If an entire row/column is NA, the result will be first index.

idxmax : Series