Merge two pandas.core.indexes.multi.MultiIndex

Question

I want to concat two multindex columns:

a = pd.MultiIndex.from_product([ ["vowels"], ["a","e"] ])
b = pd.MultiIndex.from_product( [ ["consonants"], ["b","c",] ] )
a + b 
   MultiIndex([('vowels', 'a'),
              ('vowels', 'e'),
              ('consonants', 'b'),
              ('consonants', 'c')],
             )

Answer 1

Use Index.append:

c = a.append(b)
print (c)
MultiIndex([(    'vowels', 'a'),
            (    'vowels', 'e'),
            ('consonants', 'b'),
            ('consonants', 'c')],
           )