AttributeError thrown when calling metrics.pairwise_distances with binary metrics and Y is None

Description

AttributeError thrown when calling metrics.pairwise_distances with binary metrics if Y is None.

Steps/Code to Reproduce

import numpy as np
import sklearn
binary_data = np.array((0, 0, 0, 0, 0, 1, 
                        1, 0, 0, 1, 1, 0),
                       dtype = "bool").reshape((2, 6))
sklearn.metrics.pairwise_distances(binary_data, metric="jaccard")

Expected Results

No error. Should return a numpy.ndarray of shape (2, 2) containing the pairwise distances.

Actual Results

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-21-fa618e0f7808> in <module>
----> 1 sklearn.metrics.pairwise_distances(binary_data, metric="jaccard")

e:\dev\python\anaconda\envs\umap\lib\site-packages\sklearn\metrics\pairwise.py in pairwise_distances(X, Y, metric, n_jobs, **kwds)
   1562         dtype = bool if metric in PAIRWISE_BOOLEAN_FUNCTIONS else None
   1563 
-> 1564         if dtype == bool and (X.dtype != bool or Y.dtype != bool):
   1565             msg = "Data was converted to boolean for metric %s" % metric
   1566             warnings.warn(msg, DataConversionWarning)

AttributeError: 'NoneType' object has no attribute 'dtype'

Versions

machine: Windows-10-10.0.17134-SP0
python: 3.7.3 (default, Apr 24 2019, 15:29:51) [MSC v.1915 64 bit (AMD64)]
sklearn: 0.21.0
numpy: 1.16.3
scipy: 1.2.1

This worked correctly in sklearn version 0.20.3. I think the problem was introduced in https://github.com/scikit-learn/scikit-learn/commit/4b9e12e73b52382937029d29759976c3ef4aee3c#diff-dd76b3805500714227411a6460b149a8: there is now a code path where Y has its dtype checked without any prior check as to whether Y is None.

[annikagable]

I’m sorry, it seems to be a slightly different issue because it only occurs when the array is wrapped in a pandas dataframe. Pandas version is 1.0.3

import numpy as np
import sklearn.metrics
import pandas as pd
binary_data = np.array((0, 0, 0, 0, 0, 1, 
                        1, 0, 0, 1, 1, 0),
                       dtype = "bool").reshape((2, 6))
binary_data = pd.DataFrame(binary_data)
sklearn.metrics.pairwise_distances(binary_data, metric="jaccard")

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-3-7203f3b805a8> in <module>
      6                        dtype = "bool").reshape((2, 6))
      7 binary_data = pd.DataFrame(binary_data)
----> 8 sklearn.metrics.pairwise_distances(binary_data, metric="jaccard")

/mnt/mnemo4/annika/anaconda3/envs/py38_sklearn/lib/python3.8/site-packages/sklearn/metrics/pairwise.py in pairwise_distances(X, Y, metric, n_jobs, **kwds)
   1569 
   1570         if (dtype == bool and
-> 1571                 (X.dtype != bool or (Y is not None and Y.dtype != bool))):
   1572             msg = "Data was converted to boolean for metric %s" % metric
   1573             warnings.warn(msg, DataConversionWarning)

/mnt/mnemo4/annika/anaconda3/envs/py38_sklearn/lib/python3.8/site-packages/pandas/core/generic.py in __getattr__(self, name)
   5272             if self._info_axis._can_hold_identifiers_and_holds_name(name):
   5273                 return self[name]
-> 5274             return object.__getattribute__(self, name)
   5275 
   5276     def __setattr__(self, name: str, value) -> None:

AttributeError: 'DataFrame' object has no attribute 'dtype'

[jnothman]

Can you please open a new issue for this since it is a distinct issue?