Pandas: select rows where two columns are different

Question

Suppose I have a dataframe as below

a  b  c  
1  1  45
0  2  74
2  2  54
1  4  44

Now I want the rows where column a and b are not same. So

Answer 1

I am a fan of readability, use query:

df.query('a != b')

Output:

   a  b   c
1  0  2  74
3  1  4  44