how to set a column as index in python code example

Example 1: pandas set a column as index

df = pd.DataFrame({'month': [1, 4, 7, 10],
                   'year': [2012, 2014, 2013, 2014],
                   'sale': [55, 40, 84, 31]})

df.set_index('month')

Example 2: set index to column pandas

df = df.set_index('col')
df['col'] = df.index

Example 3: how to change indeces in pandas dataframe

>>> df.set_index('month')
       year  sale
month
1      2012    55
4      2014    40
7      2013    84
10     2014    31