查询熊猫Dataframe中的错误

Question

I am facing an issue with my code using queries on simple pandas DataFrame, I am sure I am missing a tiny detail. Can you guys help me with this?

I don't understand why I've only NAN values.

Answer 1

You can change [['date']] to [date] for select Series instead one column DataFrame .

Sample :

df = pd.DataFrame({'A':[1,2,3]})

print (df['A'])
0    1
1    2
2    3
Name: A, dtype: int64

print (df[['A']])
   A
0  1
1  2
2  3

print (df[df['A'] == 1])
   A
0  1

print (df[df[['A']] == 1])
     A
0  1.0
1  NaN
2  NaN