Use reset_index() on DataFrame: returns new DataFrame with labeling information in the columns under the index names
See https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.reset_index.html
Can be useful e.g. when creating a new dataframe by selecting the rows from another dataframe, causing some of the indices to be out of order. By using reset_index() it will set the indices in order, starting from 0, and make it easier for us to work with the dataframe. Or when was changed to other values from integers, use reset_index() to convert back to integers. (https://discuss.codecademy.com/t/when-should-i-use-reset-index-in-pandas/354480
import pandas as pd
import numpy as np
df = pd.DataFrame([('bird', 389.0),
('bird', 24.0),
('mammal', 80.5),
('mammal', np.nan)],
index=['falcon', 'parrot', 'lion', 'monkey'],
columns=('class', 'max_speed'))
df
# class max_speed
# falcon bird 389.0
# parrot bird 24.0
# lion mammal 80.5
# monkey mammal NaN
df.loc['falcon',:]
# class bird
# max_speed 389
# Name: falcon, dtype: object
df.index
# Index(['falcon', 'parrot', 'lion', 'monkey'], dtype='object')