how do I drop NA within pandas.DataFrame.query

Question

consider the df

df = pd.DataFrame(dict(A=[-1, 0, 1, np.nan, 2, np.nan, 3, 4]))

I can drop NA like this

df.dropna()

but how do I do it within the query method

df.query('A is not null')

doesn't work... what does?

Answer 1

Idea #2: what's distinctive about NaNs is that they're not equal to themselves:

In [22]: df.query("A == A")
Out[22]: 
     A
0 -1.0
1  0.0
2  1.0
4  2.0
6  3.0
7  4.0

(The original idea #1 was to use df.query("A.notnull()"), but that only worked because numexpr wasn't installed in that environment, which limits the usefulness of query in the first place.)