Matthews correlation coefficient metric throws misleading division by zero RuntimeWarning #16924
Description
Description
With tested values all equal, sklearn.metrics.matthews_corrcoef throws a RuntimeWarning reporting a division by zero. This behavior was already reported in #1937 and reported fixed, but reappears in recent versions.
Steps/Code to Reproduce
The snippet below reproduces the warning.
import sklearn.metrics
trues = [1,0,1,1,0]
preds = [0,0,0,0,0]
sklearn.metrics.matthews_corrcoef(trues, preds)Expected Results
No warning is thrown.
Actual Results
The following warning is thrown:
C:\anaconda\envs\sklearn-test\lib\site-packages\sklearn\metrics\_classification.py:900: RuntimeWarning: invalid value encountered in double_scalars
mcc = cov_ytyp / np.sqrt(cov_ytyt * cov_ypyp)
Versions
System:
python: 3.8.2 (default, Mar 25 2020, 08:56:29) [MSC v.1916 64 bit (AMD64)]
executable: C:\anaconda\envs\sklearn-test\python.exe
machine: Windows-10-10.0.18362-SP0
Python dependencies:
pip: 20.0.2
setuptools: 46.1.3.post20200330
sklearn: 0.22.1
numpy: 1.18.1
scipy: 1.4.1
Cython: None
pandas: None
matplotlib: None
joblib: 0.14.1