如果有相同的值，我如何对列表进行分组?

Question

我有一个这样的字典列表

[
{'id':1,'product_id':20,'price':50,'quantity':1, 'name':'product_2'},
{'id':2,'product_id':20,'price':50,'quantity':1, 'name':'product_2'},
{'id':3,'product_id':30,'price':20,'quantity':4, 'name':'product_3'},
]

我如何将这个列表分组并得到这样的结果

[
{'id':1,'product_id':20,'price':100,'quantity':2, 'name':'product_2'},
{'id':3,'product_id':30,'price':20,'quantity':4, 'name':'product_3'},
]

由于♥

Answer 1

您需要根据公共键(例如product_id)对字典进行分组。这可以通过将字典列表转换为字典的字典来实现。然后在组中每个惟一的字典实例中组合可添加的键。

aList= [
{'id':1,'product_id':20,'price':50,'quantity':1, 'name':'product_2'},
{'id':2,'product_id':20,'price':50,'quantity':1, 'name':'product_2'},
{'id':3,'product_id':30,'price':20,'quantity':4, 'name':'product_3'},
]
groups = dict()  # product_id:dictionary 
for d in aList:
group = groups.setdefault(d["product_id"],d) # add/get first occurrence
if group is not d: 
group["price"]    += d["price"]    # combine additive fields
group["quantity"] += d["quantity"] # for duplicates

aList = list(groups.values()) # convert groups back to a list
print(aList)
[{'id': 1, 'product_id': 20, 'price': 100, 'quantity': 2, 'name': 'product_2'}, 
{'id': 3, 'product_id': 30, 'price': 20, 'quantity': 4, 'name': 'product_3'}]