Join pandas dataframes based on column values
I think you need merge with default inner join, but is necessary no duplicated combinations of values in both columns:
print (df2) item_id document_id col1 col2 col30 337 10 s 4 71 1002 11 d 5 82 1003 11 f 7 0df = pd.merge(df1, df2, on=['document_id','item_id'])print (df) item_id position document_id col1 col2 col30 337 2 10 s 4 71 1002 2 11 d 5 82 1003 3 11 f 7 0But if necessary position column in position 3:
df = pd.merge(df2, df1, on=['document_id','item_id'])cols = df.columns.tolist()df = df[cols[:2] + cols[-1:] + cols[2:-1]]print (df) item_id document_id position col1 col2 col30 337 10 2 s 4 71 1002 11 2 d 5 82 1003 11 3 f 7 0