panda set index column code example
Example 1: set index to column pandas
df = df.set_index('col')
df['col'] = df.index
Example 2: add an index column pandas
import numpy as np
import pandas as pd
df = pd.DataFrame({'month': [2, 5, 8, 10],
'year': [2017, 2019, 2018, 2019],
'sale': [60, 45, 90, 36]})
df.set_index('month')