从具有重复键的字典列表中创建具有唯一键的字典列表

Question

我有一个字典列表：records = [{id:123, name:'Course A', enrolled_date:'1st Feb'},            {id:123, name:'Course A', enrolled_date:'1st Jan'},           {id:456, name:'Course B', enrolled_date:'1st Jan'}]我想根据这些数据创建一个新的字典列表。新列表应仅包含ids在该列表范围内具有唯一性的字典，例如：new_records = [{id:123, name:'Course A'},                {id:456, name:'Course B'}]这是我到目前为止尝试过的代码。它显然不起作用 - 但我已经竭尽全力纠正它。new_records = []for record in records:     new_id = record['id']    new_name = record['name']     new_dict = {'id':new_id, 'name',new_name}    If new_id not in new_records:        new_records.append(new_dict)

Answer 1

这是基于您提供的代码，但如其他评论中所述，对于大列表，它的工作速度真的很慢。

new_records = []

for record in records: 

    new_id = record['id'] 

    new_name = record['name'] 

    new_dict = {'id':new_id, 'name': new_name}

    if not any(new_record['id'] == new_id for new_record in new_records):

        new_records.append(new_dict)

Answer 2

您还可以通过使用一组已经“见过”的条目过滤数组来实现：

records = [{"id":123, "name":'Course A', "enrolled_date":'1st Feb'}, 

           {"id":123, "name":'Course A', "enrolled_date":'1st Jan'},

           {"id":456, "name":'Course B', "enrolled_date":'1st Jan'}]

seen     = set()

new_dict = [d for d in records if not(d['id'] in seen or seen.add(d['id']))]

# {'id': 123, 'name': 'Course A', 'enrolled_date': '1st Feb'}

# {'id': 456, 'name': 'Course B', 'enrolled_date': '1st Jan'}