Python Pandas - Compare Columns In Separate Dataframes, Then Delete Non-Matching Rows In 1 DataFrame

Question

I would like to compare 2 columns in different dataframes, then delete entire non-matching rows.

The 2 columns are not of the same length.

Here is a mock-up of DataFrame #1:

Here is a mock-up of DataFrame #2:

I would like to compare the ID_NUMBER columns in the 2 DataFrames, then delete entire rows in DataFrame #1 if the row value cannot be found in DataFrame #2.

Currently, my code is not working:

DataFrame1 = np.where((DataFrame1["ID_NUMBER"] == DataFrame2["ID_NUMBER"]))

Many thanks in advance!

Answer 1

You can use pandas.Series.isin with boolean indexing:

df1[df1["ID_NUMBER"].isin(df2["ID_NUMBER"])]