pandas dataframe query not working with where

I am new to pandas, I have this data frame:

df['educ1']

which gives

1        4
2        3
3        3
4        4
5        1
        ..
28461    3
28462    2
28463    3
28464    2
28465    4
Name: educ1, Length: 28465, dtype: int64

when I try querying with

dt=df[df.educ1 > 1]

It’s working fine returning multiple rows, but when I try

college_grad_mask=(df.educ1 > 1)
df.where(college_grad_mask).dropna().head()

It gives 0 rows, I wonder what is wrong here?

>Solution :

You likely have NaNs in many columns, try to subset:

df.where(college_grad_mask).dropna(subset=['educ1']).head()

Or better:

df[college_grad_mask].head()