CODEWITHSUNDEEP
pythonpandasdataframe
Deshwal
Deshwal

Reputation: 4152

Change index inside multi level hierarchy Pandas Dataframe

I have a DataFrame that is multi level and having 2 levels named Outer Groups, Inner Numbers. I want to change the Index of Inner Numbers.

outside='g1 g1 g1 g2 g2 g2'.split()
inside='1 2 3 1 2 3'.split()
hier_index=list(zip(outside,inside))
hier_index= pd.MultiIndex.from_tuples(hier_index)
df=pd.DataFrame(np.random.randn(6,3), hier_index, ['a','b','c'])

df.index.names = ['Outer Group', 'Inner Numbers']

So my DataFrame ha outer g1, g2 and inner 1,2,3 1,2,3. I want to change the names of these as I am trying to learn. I do not want any shortcuts , Waht I want ot learn is how to

  1. change g1,g2 into X,Y
  2. Change g1(123) -> X(a,b,c)
  3. Change the label of columns such as Outer Groups -> Level 1 and Inner Numbers -> Level 2

Upvotes: 1

Views: 244

Answers (1)

jezrael
jezrael

Reputation: 862901

You can use rename with dictionary and specify levels, for change index names is possible use DataFrame.rename_axis:

df = df.rename({'g1':'X','g2':'Y'}, level=0)
df = df.rename({'1':'a','2':'b', '3':'c'}, level=1)
df = df.rename_axis(['Level 1','Level 2'])
print (df)
                        a         b         c
Level 1 Level 2                              
X       a       -1.085631  0.997345  0.282978
        b       -1.506295 -0.578600  1.651437
        c       -2.426679 -0.428913  1.265936
Y       a       -0.866740 -0.678886 -0.094709
        b        1.491390 -0.638902 -0.443982
        c       -0.434351  2.205930  2.186786

Or create new MultiIndex by MultiIndex.from_product and reassign back (lengths of both lists for new levels has to be same like original):

mux = pd.MultiIndex.from_product([['X','Y'], ['a','b','c']], names=['Level 1','Level 2'])
df.index = mux
print (df)
                        a         b         c
Level 1 Level 2                              
X       a       -1.085631  0.997345  0.282978
        b       -1.506295 -0.578600  1.651437
        c       -2.426679 -0.428913  1.265936
Y       a       -0.866740 -0.678886 -0.094709
        b        1.491390 -0.638902 -0.443982
        c       -0.434351  2.205930  2.186786

Upvotes: 2

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