how to set index pandas
# assignment copy df = df.set_index('month') # or inplace df.set_index('month', inplace=True) # year sale month month year sale # 0 2012 55 1 1 2012 55 # 1 2014 40 4 => 4 2014 40 # 2 2013 84 7 7 2013 84 # 3 2014 31 10 10 2014 31