pandas get rows which are NOT in other dataframe

Question

I\'ve two pandas data frames which have some rows in common.

Suppose dataframe2 is a subset of dataframe1.

How can I get the rows of dataframe1 which

Answer 1

extract the dissimilar rows using the merge function

df = df.merge(same.drop_duplicates(), on=['col1','col2'], 
               how='left', indicator=True)

save the dissimilar rows in CSV

df[df['_merge'] == 'left_only'].to_csv('output.csv')