Python Pandas & operator not returning right values

Question

In the code:

df = pd.DataFrame([[False, 0], [False, 1], [False, 2], [False, 2], [False, 3], [False, 4], [False, 5]], 
        columns=['cond1', 'cond2'])
df['test'] = (~df['cond1']) & (df['cond2'])

I'm expecting to get in the test column the value True in all rows except the first, as the truthy value of any number but 0 is True. However, I'm getting False where the value in cond2 is 2 or 4. Why?

The output of the above code:

   cond1 cond2 test

0  False 0     False 

1  False 1     True 

2  False 2     False 

3  False 2     False 

4  False 3     True 

5  False 4     False 

6  False 5     True

I makes sense if you see `&` as the bitwise operator, not boolean. — Quang Hoang, May 20 '21 at 13:44

score 1 · Answer 1 · edited May 20 '21 at 18:38

When you're doing "&" operation with pandas column, python can't interpret the other numbers. It's doing set operation instead of boolean operation. Therefore, you need to help it by converting to bool the second column:

df = pd.DataFrame([[False, 0], [False, 1], [False, 2], [False, 2], [False, 3], [False, 4], [False, 5]], 
        
columns=['cond1', 'cond2'])

df['test'] = (~df['cond1']) & ((df['cond2'].astype(bool)))

Python Pandas & operator not returning right values

1 Answers1