Pandas DataFrame Add column to index without resetting

PythonDataframePandas

Python Problem Overview

how do I add 'd' to the index below without having to reset it first?

from pandas import DataFrame
df = DataFrame( {'a': range(6), 'b': range(6), 'c': range(6)} )
df.set_index(['a','b'], inplace=True)
df['d'] = range(6)

# how do I set index to 'a b d' without having to reset it first?
df.reset_index(['a','b','d'], inplace=True)
df.set_index(['a','b','d'], inplace=True)

df

Python Solutions

Solution 1 - Python

We added an append option to set_index. Try that.

The command is:

df.set_index(['d'], append=True)

(we don't need to specify ['a', 'b'], as they already are in the index and we're appending to them)

Solution 2 - Python

Your code is not valid, reset_index has no inplace argument in my version of pandas (0.8.1). The following achieves what you want but there's probably a more elegant way, but you've not provided enough information as to why you are avoiding the reset_index.

df2.index = MultiIndex.from_tuples([(x,y,df2['d'].values[i]) for i,(x,y) in enumerate(df2.index.values)])

HTH

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
Questionuser1441053View Question on Stackoverflow
Solution 1 - PythonWes McKinneyView Answer on Stackoverflow
Solution 2 - PythonRuiDCView Answer on Stackoverflow