How to sort values in a MultiIndex pandas dataframe?

Question

I have a pandas DataFrame with MultiIndex. I want to sort the values of a column, and compare values in index level0. If the value is the maximum, the id should be 1, and if the value is the secondary, the id should be 2. Finally, output its sorted id.

For example:

arrays = [['bar', 'bar','bar', 'baz', 'baz', 'foo', 'foo','foo', 'foo','qux', 'qux'],
      ['one', 'two', 'three','one', 'two', 'one', 'two','three', 'four',  'one', 'two']]
df = pd.DataFrame(np.random.randn(11), index=arrays,columns=['values'])
df

output:

            values
bar one     -1.098567
    two     -0.936011
    three   -0.654245
baz one     -0.637409
    two     -0.439939
foo one      0.238114
    two      1.146573
    three   -0.512294
    four    -0.611913
qux one     -0.481083
    two      0.515961

Finally, I want this:

            values      sort
bar one     -1.098567      3
    two     -0.936011      2
    three   -0.654245      1
baz one     -0.637409      2
    two     -0.439939      1
foo one      0.238114      2
    two      1.146573      1
    three   -0.512294      3
    four    -0.611913      4
qux one     -0.481083      2
    two      0.515961      1

Answer 1

Group on the first level (ie level 0), and then rank them in descending order.

>>> df.assign(sort=df.groupby(level=0).rank(ascending=False))
             values  sort
bar one   -1.098567     3
    two   -0.936011     2
    three -0.654245     1
baz one   -0.637409     2
    two   -0.439939     1
foo one    0.238113     2
    two    1.146573     1
    three -0.512295     3
    four  -0.611913     4
qux one   -0.481083     2
    two    0.515961     1