pandas, how to access multiIndex dataframe?

Question

Show my code

>>> df = pd.DataFrame({'key1': ['a', 'a', 'b', 'b', 'a'], \
                   'key2': ['one', 'two', 'one', 'two', 'one'], \
                   'data1': np.random.randn(5), \
                   'data2': np.random.randn(5)})

>>> new_df = df.groupby(['key1', 'key2']).mean().unstack()
>>> print new_df
         data1               data2
key2       one       two       one       two
key1
a    -0.070742 -0.598649 -0.349283 -1.272043
b    -0.109347 -0.097627 -0.641455  1.135560 
>>> print new_df.columns
MultiIndex(levels=[[u'data1', u'data2'], [u'one', u'two']],
       labels=[[0, 0, 1, 1], [0, 1, 0, 1]],
       names=[None, u'key2'])

As you can see, the MultiIndex dataframe is different with normal dataframes, so how to access the data in the MultiIndex dataframe.

Though it's not easy to follow the documentation (explanations buried into an "advanced indexing" section), keep in mind multilevel indexing is based on tuple indices, hence accessing data requires loc and tuples, even if there are ambiguous shortcuts not using loc and even not using tuples. — mins
– mins, Commented Jan 2, 2021 at 16:15

Zhenhao Chen · Accepted Answer · 2016-04-23 05:53:36Z

27

Accessing data in multiindex dataframe is similar to the way on a general dataframe. For example, if you want to read data at (a, data1.two), you can simply do: new_df['data1']['two']['a'] or new_df.loc['a', ('data1', 'two')]

Please read the official docs for more details.

answered Apr 23, 2016 at 5:53

Zhenhao Chen

5354 silver badges6 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

sounish nath · Accepted Answer · 2021-10-20 04:16:58Z

-2

This might helps you to know and visualize

unstacked = multi_indexDataFrame.unstack().dropna()
unstacked.plot(kind="bar")

answered Oct 20, 2021 at 4:16

sounish nath

6815 silver badges3 bronze badges

Collectives™ on Stack Overflow

pandas, how to access multiIndex dataframe?

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related