Get specific index from MultiIndex of Pandas data frame as list

Question

I want to to get a specific index of a Pandas data frame with a MultiIndex as a list.

Given the example

import pandas as pd; import numpy as np
np.random.seed(42)
df = pd.DataFrame(np.random.randint(5, size=(5, 4)), columns=list('ABCD'))
df.set_index(['A', 'B'], inplace=True)

in which df is defined as

I want to extract

[4 1 4 1 4]

which corresponds to the second index B. How can this be done?

BENY · Accepted Answer · 2018-10-22 14:56:45Z

4

Using get_level_values

df.index.get_level_values(level=1).tolist()
Out[1040]: [4, 1, 4, 1, 4]

Or reset_index

df.reset_index(level=1).B.tolist()
Out[1041]: [4, 1, 4, 1, 4]

answered Oct 22, 2018 at 14:56

BENY

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Comments

Felix · Accepted Answer · 2018-10-22 16:44:11Z

0

This solution uses stacking through np.stack() and slicing:

np.stack(df.index.values, axis=0)[:,1]

edited Oct 22, 2018 at 16:44

answered Oct 22, 2018 at 14:55

Felix

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