Find row number in column where it matches any other value in column of other dataframe

Question

I have a code:

import pandas as pd
import numpy as np

arm_1_and_m1_df = pd.DataFrame({ \'record_id\': [1, 4, 3, np.nan],
                   \'two\': [1, 2, np.n         


        

Answer 1

Try isin and slicing on index

a_index = (redcap_final_arm1_data.index[redcap_final_arm1_data.record_id
                                           .isin(arm_1_and_m1_df.record_id)].tolist())

output:

Out[1355]: [0, 2, 3, 9]