How can I change a specific row label in a Pandas dataframe?

Question

I have a dataframe such as:

      0     1    2    3    4    5
0  41.0  22.0  9.0  4.0  2.0  1.0
1   6.0   1.0  2.0  1.0  1.0  1.0
2   4.0   2.0  4.0  1.0  0.0  1.0
3   1.0   2.0  1.0  1.0  1.0  1.0
4   5.0   1.0  0.0  1.0  0.0  1.0
5  11.4   5.6  3.2  1.6  0.8  1.0

Where the final row contains averages. I would like to rename the final row label to "A" so that the dataframe will look like this:

      0     1    2    3    4    5
0  41.0  22.0  9.0  4.0  2.0  1.0
1   6.0   1.0  2.0  1.0  1.0  1.0
2   4.0   2.0  4.0  1.0  0.0  1.0
3   1.0   2.0  1.0  1.0  1.0  1.0
4   5.0   1.0  0.0  1.0  0.0  1.0
A  11.4   5.6  3.2  1.6  0.8  1.0

I understand columns can be done with df.columns = . . .. But how can I do this with a specific row label?

Answer 1

You can get the last index using negative indexing similar to that in Python

last = df.index[-1]

Then

df = df.rename(index={last: 'a'})

Edit: If you are looking for a one-liner,

df.index = df.index[:-1].tolist() + ['a']

Answer 2

use index attribute:

 df.index = df.index[:-1].append(pd.Index(['A']))