使用具有重复键的字典列表创建具有唯一键的字典列表

Question

我有一个词典列表：

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'}]

我想从这些数据中创建一个新的字典列表。 新列表应该只包含在该列表范围内具有唯一ids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 - 但我已经用尽所有努力来纠正它。

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，但对于大型列表，它的工作确实非常慢，如其他注释中所述。

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

您也可以通过使用一组已经“看到”的条目过滤数组来完成此操作：

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'}