Cannot use .ix in IntervaIndex('pandas._libs.interval.IntervalTree' object has no attribute 'get_value')

[Janhonho]

Code Sample, a copy-pastable example if possible

x = pd.Series([-2.801298, -2.882724, -3.007899, -2.704554, -3.398761, -2.805034, -2.87554, -2.805034, -2.886459, -2.471618])
y= pd.Series([0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
init_cut = pd.qcut(x, 5, duplicates='drop')
retbin = pd.Series(init_cut.values.categories).sort_values()
retbin.iloc[0] = pd.Interval(-np.inf, retbin.iloc[0].right)
retbin.iloc[-1] = pd.Interval(retbin.iloc[-1].left, np.inf)
init_cut = pd.cut(x, pd.IntervalIndex(retbin))
init_cut = init_cut.astype(object)
bin_df = pd.crosstab(index=init_cut, columns=y)
bin_df = bin_df.reindex(retbin)
bin_df = bin_df.sort_index()
bin_df = bin_df.fillna(0.0)
bin_df['nbin'] = np.nan

Problem description

bin_df =
col_0 0 nbin
(-inf, -2.911] 2 NaN
(-2.911, -2.878] 2 NaN
(-2.878, -2.805] 3 NaN
(-2.805, -2.782] 1 NaN
(-2.782, inf] 2 NaN

if I use bin_df.ix[0:2,0], I got an error like:

Traceback (most recent call last):
  File "D:\anaconda\lib\site-packages\IPython\core\interactiveshell.py", line 2961, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-12-1ae8ba69565c>", line 1, in <module>
    bin_df.ix[0:1,'nbin']
  File "D:\PyTest\venv\lib\site-packages\pandas\core\indexing.py", line 125, in __getitem__
    values = self.obj._get_value(*key)
  File "D:\PyTest\venv\lib\site-packages\pandas\core\frame.py", line 2827, in _get_value
    return engine.get_value(series._values, index)
AttributeError: 'pandas._libs.interval.IntervalTree' object has no attribute 'get_value'

the version is 0.25.0
but it works well in 0.24.x

Expected Output

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]

[Janhonho]

In fact I've got another problem beside, I cannot use:
init_cut = init_cut.astype(pd.Interval)
I've got another error:
Traceback (most recent call last):
File "D:\anaconda\lib\site-packages\IPython\core\interactiveshell.py", line 2961, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)
File "", line 1, in
init_cut.astype(pd.Interval)
File "D:\PyTest\venv\lib\site-packages\pandas\core\generic.py", line 5883, in astype
dtype=dtype, copy=copy, errors=errors, **kwargs
File "D:\PyTest\venv\lib\site-packages\pandas\core\internals\managers.py", line 581, in astype
return self.apply("astype", dtype=dtype, **kwargs)
File "D:\PyTest\venv\lib\site-packages\pandas\core\internals\managers.py", line 438, in apply
applied = getattr(b, f)(**kwargs)
File "D:\PyTest\venv\lib\site-packages\pandas\core\internals\blocks.py", line 557, in astype
return self._astype(dtype, copy=copy, errors=errors, values=values, **kwargs)
File "D:\PyTest\venv\lib\site-packages\pandas\core\internals\blocks.py", line 612, in _astype
dtype = pandas_dtype(dtype)
File "D:\PyTest\venv\lib\site-packages\pandas\core\dtypes\common.py", line 2067, in pandas_dtype
raise TypeError("dtype '{}' not understood".format(dtype))
TypeError: dtype '<class 'pandas._libs.interval.Interval'>' not understood

which is ok in version 0.23.4
but error in version 0.24.x and later version

[Janhonho]

Any can help me....

[jorisvandenbossche]

@Janhonho for the first bug, there is a PR to fix this in 0.25.1: #27926. However, note that you are using ix which is deprecated and will be removed in the next major version. So in this case you can actually rather do bin_df.iloc[0:2,0].

For the second one (init_cut.astype(pd.Interval)), that only worked by accident, where pd.Interval (which is not a data type object, but the scalar interval class) was interpreted as general 'object' dtype. So to have the same as you had before, you can now do init_cut.astype(object) instead. But note that this does not convert to an actual interval type.