audmetric.utils.infer_labels() can fail for NaN #12
Description
If you have a mixture of string entries and NaN, audmetric.utils.infer_labels() will fail:
>>> audmetric.utils.infer_labels(['a', 'b'], ['a', np.NaN])
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-6-c5231a7963ad> in <module>
----> 1 audmetric.utils.infer_labels(['a', 'b'], ['a', np.NaN])
~/git/audeering/audmetric/audmetric/core/utils.py in infer_labels(truth, prediction)
33
34 """
---> 35 return sorted(list(set(truth) | set(prediction)))
36
37
TypeError: '<' not supported between instances of 'str' and 'float'whereas the expected result should be ['a', 'b'].