BUG: min on non-numeric data with nans · Issue #4147 · pandas-dev/pandas (original) (raw)
Min doesn't seem to work as expected with NaNs and non-numeric data:
In [1]: s = pd.Series(['alpha', np.nan, 'charlie', 'delta'])
In [2]: s
Out[2]:
0 alpha
1 NaN
2 charlie
3 delta
dtype: object
In [3]: s.min() # by default docstring suggests this should skipnan
Out[3]: inf
The hack/workaround is to exclude them, perhaps we should special case this in the code:
In [4]: s[s.notnull()].min()
Out[4]: 'alpha'
From discussion on this pandas SO question. and I also posted a corresponding numpy issue: numpy/numpy#3508.