比较列表中嵌套字典的最佳方法，Python

Question

我正在查询公共端点以获取返回带有嵌套字典的列表的各种交换的汇率。 我最感兴趣的是嵌套字典中的关键“金额”字段。 我正在努力想出一个解决方案来存储在变量中具有最多“数量”值的嵌套字典。 任何想法都会非常有帮助。 我正在用头撞墙。

这是清单：

list_with_nested_dicts = [{"partner":"simpleswap","amount":0,"currency":"cel","supportRate":3,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"simpleswap","amount":0,"currency":"cel","supportRate":3,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"stealthex","amount":37.90346104,"currency":"cel","supportRate":2,"duration":66.62083333333334,"fixed":true,"min":39.91443225,"max":2550.215226,"exists":true,"id":""},{"partner":"stealthex","amount":37.20972396,"currency":"cel","supportRate":2,"duration":23.158333333333335,"fixed":false,"min":77.82938688,"max":25209.49720665,"exists":true,"id":""},{"partner":"godex","amount":0,"currency":"cel","supportRate":0,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"changenow","amount":37.2077365,"currency":"cel","supportRate":2,"duration":11.08859649122807,"fixed":false,"min":56.60646516,"max":25259.88795509,"exists":true,"id":""},{"partner":"changelly","amount":0,"currency":"cel","supportRate":1,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"changelly","amount":0,"currency":"cel","supportRate":1,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"instaswap","amount":0,"currency":"cel","supportRate":2,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"exolix","amount":0,"currency":"cel","supportRate":0,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"fixedfloat","amount":0,"currency":"cel","supportRate":3,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"switchain","amount":0,"currency":"cel","supportRate":2,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"changehero","amount":0,"currency":"cel","supportRate":3,"duration":56.41111111111111,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"changehero","amount":0,"currency":"cel","supportRate":3,"duration":2.4833333333333334,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"binance","amount":0,"currency":"cel","supportRate":2,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"nexchange","amount":0,"currency":"cel","supportRate":3,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"letsexchange","amount":0,"currency":"cel","supportRate":2,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""},{"partner":"letsexchange","amount":0,"currency":"cel","supportRate":2,"duration":0,"fixed":false,"min":0,"max":0,"exists":false,"id":""},{"partner":"alfacash","amount":0,"currency":"cel","supportRate":3,"duration":0,"fixed":true,"min":0,"max":0,"exists":false,"id":""}]

数量最多的字典是：

{"partner":"stealthex","amount":37.90346104,"currency":"cel","supportRate":2,"duration":66.62083333333334,"fixed":true,"min":39.91443225,"max":2550.215226,"exists":true,"id":""}

Answer 1

使用max的key参数：

from operator import  itemgetter
res = max(list_with_nested_dicts, key=itemgetter("amount"))
print(res)

输出

{'partner': 'stealthex', 'amount': 37.90346104, 'currency': 'cel', 'supportRate': 2, 'duration': 66.62083333333334, 'fixed': True, 'min': 39.91443225, 'max': 2550.215226, 'exists': True, 'id': ''}

从文档：

key 参数指定一个单参数排序函数，就像用于 list.sort()

请注意，不需要使用operator.itemgetter ，您可以简单地使用 lambda 函数作为key的值：

max(list_with_nested_dicts, key=lambda x: x["amount"])

Answer 2

您的 dict 不是有效的 Python 表达式，例如，未定义true （除非您之前已定义）。 您可能想用True替换true ，用False替换false 。

您可以将max与key参数一起使用：

from operator import itemgetter
d = max(list_with_nested_dicts, key=itemgetter('amount'))
print(d) # 083333333334, 'fixed': True, 'min': 39.91443225, 'max': 2550.215226, 'exists': True, 'id': ''}

Answer 3

试试这个： 但是你需要用 True 替换 'true'，用 'False' 替换 'false' 才能使这段代码正常工作。

list_with_nested_dicts.sort(key=lambda a: a['amount'])
print(list_with_nested_dicts[-1])