How to use numpy vectorization to find different data columns in the same column of two huge dataframes?

I have two dataframes, df1 and df2, both have the same column date. The date column of df1 has about tens of millions of rows, and the date column of df1 is incomplete and may be duplicated. df2 is about a few thousand rows. The date column of df2 is complete and not repeated. How to use numpy vectorization to find out the date1 data that does not exist in df1 but exists in df2 and generate an numpy ndarray? I tried np.where and groupby.size, but I couldn’t find the correct way to use them.


You can also use this on top of recommended solutions in comments: