通过汇总Python中的现有列表来创建新列表
通过汇总Python中的现有列表来创建新列表
提问于 2021-08-05 07:18:08
我在Python中有一个类似这样的列表：
my_list = [
{"id":1,"symbol":"ABC","quantity":100},
{"id":2,"symbol":"PQR","quantity":500},
{"id":3,"symbol":"ABC","quantity":300},
{"id":1,"symbol":"XYZ","quantity":320},
{"id":3,"symbol":"PQR","quantity":800},
]我想总结一个具有相似符号的量，并创建一个新的列表。new_list将如下所示：
new_list = [
{ "symbol":"ABC","total_quantity":400,"ids":"1 3"}
{ "symbol":"PQR","total_quantity":1300,"ids":"2 3"}
{ "symbol":"XYZ","total_quantity":320,"ids":"1"}
]我是Python的新手，尝试过一些方法，但都不能工作。我可以尝试实现什么呢？
回答 4
Stack Overflow用户
发布于 2021-08-05 07:29:38
如果您可以使用pandas，您可以采用这种方法
import pandas as pd
df = pd.DataFrame.from_dict(my_list)
df1 = df.groupby('symbol').agg({'quantity':'sum',
'id':lambda x: ' '.join(map(str, x))}).reset_index()输出：
{'0': {'symbol': 'ABC', 'quantity': 400, 'id': '1 3'},
'1': {'symbol': 'PQR', 'quantity': 1300, 'id': '2 3'},
'2': {'symbol': 'XYZ', 'quantity': 320, 'id': '1'}}Stack Overflow用户
发布于 2021-08-05 07:30:04
一个很好的解决方案是使用一个便于按symbol分组的defaultdict，您只需要最后一步来构建ids
from collections import defaultdict
my_list = [{"id": 1, "symbol": "ABC", "quantity": 100},
{"id": 2, "symbol": "PQR", "quantity": 500},
{"id": 3, "symbol": "ABC", "quantity": 300},
{"id": 1, "symbol": "XYZ", "quantity": 320},
{"id": 3, "symbol": "PQR", "quantity": 800}, ]
expected = defaultdict(lambda: {'symbol': '', 'ids': [], "total_quantity": 0})
for row in my_list:
expected[row['symbol']]['symbol'] = row['symbol']
expected[row['symbol']]['ids'].append(str(row['id']))
expected[row['symbol']]['total_quantity'] += row['quantity']
result = [{**x, 'ids': " ".join(x['ids'])} for x in expected.values()]Stack Overflow用户
发布于 2021-08-05 07:36:26
这样的东西对你来说应该是有效的：
my_list = [
{"id":1,"symbol":"ABC","quantity":100},
{"id":2,"symbol":"PQR","quantity":500},
{"id":3,"symbol":"ABC","quantity":300},
{"id":1,"symbol":"XYZ","quantity":320},
{"id":3,"symbol":"PQR","quantity":800},
]
new_list = []
for item in my_list:
if item["symbol"] not in [new_item["symbol"] for new_item in new_list]:
new_list.append({"symbol":item["symbol"],"total_quantity":item["quantity"],"ids":str(item["id"])})
else:
for new_item in new_list:
if item["symbol"] == new_item["symbol"]:
new_item["total_quantity"] += item["quantity"]
new_item["ids"] += " "+str(item["id"])
break
print(new_list)页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/68662193
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