Мои данные выглядят следующим образом:
| Location | ticketPeriod | UserID | ticketUses | Demographic | Date |
|----------|--------------|--------|------------|-------------|------------|
| London | Day | 1 | 1 | Adult | 21/03/2019 |
| London | Day | 1 | 2 | Adult | 06/02/2019 |
| Glasgow | Day | 1 | 1 | Adult | 04/04/2019 |
| Glasgow | Day | 12 | 3 | Child | 03/04/2019 |
| Glasgow | Day | 3 | 1 | Child | 04/01/2019 |
| Glasgow | Week | 2 | 3 | Child | 27/01/2019 |
| Glasgow | Month | 3 | 3 | Concession | 04/04/2019 |
| London | Annual | 5 | 2 | Concession | 15/02/2019 |
| London | Quarterly | 5 | 1 | Adult | 13/02/2019 |
| Cardiff | Annual | 5 | 1 | Adult | 24/01/2019 |
| Cardiff | Quarterly | 1 | 1 | Child | 11/03/2019 |
| London | Week | 3 | 2 | Child | 04/04/2019 |
| Cardiff | Week | 12 | 4 | Adult | 04/04/2019 |
| London | Annual | 3 | 9 | Adult | 04/04/2019 |
я пытаюсь сгруппировать данные, чтобы получить минимальную дату и количество ticketUse для каждой группы, но сохранить поле даты, как показано ниже;
| Location | ticketPeriod | UserID | ticketUses | Demographic | Date | MinDate | countTicketUses |
|----------|--------------|--------|------------|-------------|------------|------------|-----------------|
| Cardiff | Annual | 5 | 1 | Adult | 24/01/2019 | 24/01/2019 | 1 |
| Cardiff | Quarterly | 1 | 1 | Child | 11/03/2019 | 11/03/2019 | 1 |
| Cardiff | Week | 12 | 4 | Adult | 04/04/2019 | 04/04/2019 | 4 |
| Glasgow | Day | 3 | 1 | Child | 04/04/2019 | 04/01/2019 | 5 |
| Glasgow | Day | 3 | 3 | Child | 03/04/2019 | 04/01/2019 | 5 |
| Glasgow | Day | 3 | 1 | Child | 04/01/2019 | 04/01/2019 | 5 |
| Glasgow | Week | 2 | 3 | Child | 27/01/2019 | 27/01/2019 | 6 |
| Glasgow | Week | 3 | 3 | Child | 04/04/2019 | 27/01/2019 | 6 |
| London | Day | 1 | 1 | Adult | 21/03/2019 | 06/02/2019 | 17 |
| London | Day | 1 | 2 | Adult | 06/02/2019 | 06/02/2019 | 17 |
| London | Day | 5 | 2 | Adult | 15/02/2019 | 06/02/2019 | 17 |
| London | day | 5 | 1 | Adult | 13/02/2019 | 06/02/2019 | 17 |
| London | day | 3 | 2 | Adult | 04/04/2019 | 06/02/2019 | 17 |
| London | day | 3 | 9 | Adult | 04/04/2019 | 06/02/2019 | 17 |
В основном эквивалент группы, мутировать в R.