title: python pandas merge dataframe
body: <p>How to merge these 2 tables by origin, destination and carrier?</p>
  <p>The first table has the column medium need and i need to add this filed into the 2 table, based on origin+destination+carrier values.
  The response should be in a new column in the 2 table.</p>
  <p>I tried to do <code>pandas.merge(1st table, 2 table)</code> but it didn't help.</p>
  <p>Please help me with this question</p>
  <p>1 table:</p>
  <p><code>{'index': {0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19}, 'origin': {0: 'NEW YORK', 1: 'NEW YORK', 2: 'NEW YORK', 3: 'NEW YORK', 4: 'NEW YORK', 5: 'NEW YORK', 6: 'NEW YORK', 7: 'NEW YORK', 8: 'NEW YORK', 9: 'NEW YORK', 10: 'NEW YORK', 11: 'NEW YORK', 12: 'NEW YORK', 13: 'NEW YORK', 14: 'NEW YORK', 15: 'NEW YORK', 16: 'NEW YORK', 17: 'NEW YORK', 18: 'NEW YORK', 19: 'NEW YORK'}, 'destination': {0: 'Aqaba', 1: 'Aqaba', 2: 'Batumi', 3: 'Benghazi', 4: 'Benghazi', 5: 'Bremerhaven', 6: 'El Khoms', 7: 'El Khoms', 8: 'El Khoms', 9: 'Jebel Ali', 10: 'Jebel Ali', 11: 'Jebel Ali', 12: 'Klaipeda', 13: 'Klaipeda', 14: 'MISURATA', 15: 'MISURATA', 16: 'MISURATA', 17: 'Novorossiysk', 18: 'Odessa', 19: 'Odessa'}, 'carrier_name': {0: 'HAPAG LLOYD', 1: 'MEDITERRANEAN SHIPPING CORP', 2: 'MEDITERRANEAN SHIPPING CORP', 3: 'CGM', 4: 'MAERSK LINES, INC.', 5: 'CGM', 6: 'CGM', 7: 'HAPAG LLOYD', 8: 'MAERSK LINES, INC.', 9: 'HAPAG LLOYD', 10: 'MAERSK LINES, INC.', 11: 'ONE NETWORK EXPRESS', 12: 'CGM', 13: 'EVERGREEN INTERNATIONAL (U S A)', 14: 'CGM', 15: 'HAPAG LLOYD', 16: 'MAERSK LINES, INC.', 17: 'MEDITERRANEAN SHIPPING CORP', 18: 'CGM', 19: 'Cosco Container Line'}, 'medium need': {0: 20.0, 1: 19.0, 2: 5.0, 3: 30.0, 4: 26.0, 5: 28.0, 6: 15.0, 7: 11.0, 8: 12.0, 9: 15.0, 10: 18.0, 11: 16.0, 12: 16.0, 13: 10.0, 14: 7.0, 15: 6.0, 16: 7.0, 17: 6.0, 18: 42.0, 19: 26.0}} </code></p>
  <p>2 table:</p>
  <p><code>{'index': {0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10, 11: 11, 12: 12, 13: 13, 14: 14, 15: 15, 16: 16, 17: 17, 18: 18, 19: 19}, 'origin': {0: 'NEW YORK', 1: 'NEW YORK', 2: 'NEW YORK', 3: 'NEW YORK', 4: 'NEW YORK', 5: 'NEW YORK', 6: 'NEW YORK', 7: 'NEW YORK', 8: 'NEW YORK', 9: 'NEW YORK', 10: 'NEW YORK', 11: 'NEW YORK', 12: 'NEW YORK', 13: 'NEW YORK', 14: 'NEW YORK', 15: 'NEW YORK', 16: 'NEW YORK', 17: 'NEW YORK', 18: 'NEW YORK', 19: 'NEW YORK'}, 'destination': {0: 'Aqaba ', 1: 'Aqaba ', 2: 'Aqaba ', 3: 'Aqaba ', 4: 'Aqaba ', 5: 'Aqaba ', 6: 'Aqaba ', 7: 'Aqaba ', 8: 'Aqaba ', 9: 'Aqaba ', 10: 'Aqaba ', 11: 'Aqaba ', 12: 'Aqaba ', 13: 'Aqaba ', 14: 'Aqaba ', 15: 'Aqaba ', 16: 'Aqaba ', 17: 'Aqaba ', 18: 'Aqaba ', 19: 'Aqaba '}, 'from_': {0: '3/22/2021', 1: '3/29/2021', 2: '4/05/2021', 3: '3/29/2021', 4: '4/05/2021', 5: '4/12/2021', 6: '3/22/2021', 7: '3/29/2021', 8: '4/12/2021', 9: '4/05/2021', 10: '4/05/2021', 11: '4/12/2021', 12: '4/12/2021', 13: '4/12/2021', 14: '3/22/2021', 15: '3/22/2021', 16: '3/22/2021', 17: '3/22/2021', 18: '4/12/2021', 19: '3/29/2021'}, 'to_': {0: '3/29/2021', 1: '4/05/2021', 2: '4/12/2021', 3: '4/05/2021', 4: '4/12/2021', 5: '4/19/2021', 6: '3/29/2021', 7: '4/05/2021', 8: '4/19/2021', 9: '4/12/2021', 10: '4/12/2021', 11: '4/19/2021', 12: '4/19/2021', 13: '4/19/2021', 14: '3/29/2021', 15: '3/29/2021', 16: '3/29/2021', 17: '3/29/2021', 18: '4/19/2021', 19: '4/05/2021'}, 'carrier_name': {0: 'MEDITERRANEAN SHIPPING CORP', 1: 'MEDITERRANEAN SHIPPING CORP', 2: 'HAPAG LLOYD', 3: 'MEDITERRANEAN SHIPPING CORP', 4: 'MEDITERRANEAN SHIPPING CORP', 5: 'MEDITERRANEAN SHIPPING CORP', 6: 'HAPAG LLOYD', 7: 'HAPAG LLOYD', 8: 'MEDITERRANEAN SHIPPING CORP', 9: 'MEDITERRANEAN SHIPPING CORP', 10: 'MAERSK LINES, INC.', 11: 'MAERSK LINES, INC.', 12: 'HAPAG LLOYD', 13: 'HAPAG LLOYD', 14: 'MAERSK LINES, INC.', 15: 'MAERSK LINES, INC.', 16: 'MEDITERRANEAN SHIPPING CORP', 17: 'HAPAG LLOYD', 18: 'CGM', 19: 'MEDITERRANEAN SHIPPING CORP'}, 'vessel_name': {0: 'MSC RANIA', 1: 'MSC RANIA', 2: 'CMA CGM IVANHOE', 3: 'SEAMAX BRIDGEPORT', 4: 'SEAMAX BRIDGEPORT', 5: 'NAVARINO', 6: 'EXPRESS ATHENS', 7: 'EXPRESS ATHENS', 8: 'NAVIOS UTMOST', 9: 'NAVIOS UTMOST', 10: 'MAERSK SEBAROK', 11: 'MAERSK COLUMBUS', 12: 'EXPRESS ROME', 13: 'EXPRESS ROME', 14: 'MAERSK ATLANTA', 15: 'MAERSK ATLANTA', 16: 'MSC RANIA', 17: 'OOCL WASHINGTON', 18: 'OOCL EUROPE', 19: 'MSC RANIA'}, 'doc_cut': {0: '3/29/2021', 1: '3/29/2021', 2: '4/9/2021', 3: '4/5/2021', 4: '4/5/2021', 5: '4/19/2021', 6: '3/29/2021', 7: '3/29/2021', 8: '4/12/2021', 9: '4/12/2021', 10: '4/6/2021', 11: '4/13/2021', 12: '4/16/2021', 13: '4/15/2021', 14: '3/26/2021', 15: '3/26/2021', 16: '3/29/2021', 17: '3/23/2021', 18: '4/15/2021', 19: '3/29/2021'}, 'container_type': {0: 'HV', 1: 'HV', 2: 'HV', 3: 'HV', 4: 'HV', 5: 'HV', 6: 'HV', 7: 'HV', 8: 'HV', 9: 'HV', 10: '45', 11: '45', 12: 'HV', 13: 'HV', 14: 'HV', 15: '45', 16: '45', 17: 'HV', 18: '2B', 19: '45'}, 'count': {0: 32, 1: 32, 2: 26, 3: 15, 4: 15, 5: 14, 6: 13, 7: 13, 8: 12, 9: 12, 10: 8, 11: 7, 12: 7, 13: 6, 14: 5, 15: 2, 16: 1, 17: 1, 18: 1, 19: 1}} </code></p>