Filtering on dataframes by equality on certain columns

Question

I want to filter through a dataframe in python of 3 columns. I want only the rows for which the first two columns are the same but not the third one. i.e.

A B C
1 4 2
1 5 3
2 3 3
3 1 1
4 3 2
2 3 5

On the above example, I would like to get only rows 3 and 6 since the first two columns match.

mozway · Answer

Use duplicated and boolean indexing:

out = df[df[['A', 'B']].duplicated(keep=False)]

output:

   A  B  C
2  2  3  3
5  2  3  5

Filtering on dataframes by equality on certain columns

1 Answers