Python - 向下迭代字典 - 有条件地向下移动树答案

【问题标题】：Python - Itterate down dictionairy - move down tree conditionallyPython - 向下迭代字典 - 有条件地向下移动树
【发布时间】：2022-01-02 16:45:09
【问题描述】：

我在下面有一些 Python 代码，它沿着树向下走，但我希望它沿着树向下工作，检查有条件地根据值采取一些路径。我想根据条件和fulfillmentChannel获取树分支的fulfillmentChannel

parsed_results['LowestLanded'] = sku_multi_sku['Summary']['LowestPrices']['LowestPrice']['LandedPrice']['Amount']['value']

这会沿着这棵树向下走，但值是因为有两个 LowestPrice 记录/字典为每个 condition 和 fulfillmentChannel 对返回一个。我想过滤condition=new 和fulfillmentChannel=Amazon，所以我只取回一条记录。当我解析 XML 数据时，我可以使用类似于 LowestPrices/LowestPrice[@condition='new'][@fulfillmentChannel='Merchant']/LandedPrice/Amount" 的代码来执行此操作，但在这里无法获得类似的代码。我如何用字典做到这一点？

 "LowestPrices":{
     "value":"\n                ",
     "LowestPrice":[
        {
           "value":"\n                    ",
           "condition":{
              "value":"new"               #condtion new
           },
           "fulfillmentChannel":{
              "value":"Amazon"            ## fulfilllmentChannel #1
           },
           "LandedPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.57"
              }
           },
           "ListingPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.57"
              }
           },
           "Shipping":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"0.00"
              }
           }
        },
        {
           "value":"\n                    ",
           "condition":{
              "value":"new"
           },
           "fulfillmentChannel":{
              "value":"Merchant"
           },
           "LandedPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.25"
              }
           },
           "ListingPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.25"
              }
           },
           "Shipping":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"0.00"
              }
           }
        }
     ]
  },

【问题讨论】：

这里是否有答案，我只需要在列表中的级别迭代/循环数据？

标签： python json python-3.x list dictionary

【解决方案1】：

您可以将list comprehensions 与条件逻辑一起用于您的目的，如下所示：

my_dict = {
    "LowestPrices": {
        "value": "\n                ",
        "LowestPrice": [{
            "value": "\n                    ",
            "condition": {
                "value": "new"
            },
            "fulfillmentChannel": {
                "value": "Amazon"
            },
            "LandedPrice": {
                "value": "\n                        ",
                "CurrencyCode": {
                    "value": "USD"
                },
                "Amount": {
                    "value": "19.57"
                }
            },
            "ListingPrice": {
                "value": "\n                        ",
                "CurrencyCode": {
                    "value": "USD"
                },
                "Amount": {
                    "value": "19.57"
                }
            },
            "Shipping": {
                "value": "\n                        ",
                "CurrencyCode": {
                    "value": "USD"
                },
                "Amount": {
                    "value": "0.00"
                }
            }
        },
            {
                "value": "\n                    ",
                "condition": {
                    "value": "new"
                },
                "fulfillmentChannel": {
                    "value": "Merchant"
                },
                "LandedPrice": {
                    "value": "\n                        ",
                    "CurrencyCode": {
                        "value": "USD"
                    },
                    "Amount": {
                        "value": "19.25"
                    }
                },
                "ListingPrice": {
                    "value": "\n                        ",
                    "CurrencyCode": {
                        "value": "USD"
                    },
                    "Amount": {
                        "value": "19.25"
                    }
                },
                "Shipping": {
                    "value": "\n                        ",
                    "CurrencyCode": {
                        "value": "USD"
                    },
                    "Amount": {
                        "value": "0.00"
                    }
                }
            }
        ]
    },
}

lowest_prices = [x for x in my_dict["LowestPrices"]["LowestPrice"] if
                 x["condition"]["value"] == "new"
                 and x["fulfillmentChannel"]["value"] == "Amazon"]

lowest_prices 是满足所需条件的所有字典的列表。如果您确定您的案例中只有一本满足条件的字典，或者您只想获取第一本的数量，您只需执行以下操作：

if len(lowest_prices) > 0:
    amount = lowest_prices[0]["LandedPrice"]["Amount"]["value"]
    print(amount)

【讨论】：

【解决方案2】：

这个问题的模型方法

from unittest import TestCase
from pydantic import BaseModel
from typing import List
  
class MdlValue(BaseModel):
    value:str
    
class MdlFulfillment(BaseModel):
    value:str
  
class MdlPrice(BaseModel):
    value:str
    CurrencyCode:MdlValue
    Amount:MdlValue
          
class MdlPrices(BaseModel):
    condition:MdlValue
    fulfillmentChannel:MdlFulfillment
    LandedPrice:MdlPrice
    ListingPrice:MdlPrice
    Shipping:MdlPrice
 
class MdlPricesList(BaseModel):
        value:str
        LowestPrice:List[MdlPrices]
           
class MdlLowestPrices(BaseModel):
    LowestPrices:MdlPricesList
    
    
data =  { 
    "LowestPrices":{
     "value":"\n                ",
     "LowestPrice":[
        {
           "value":"\n                    ",
           "condition":{
              "value":"new"               #condtion new
           },
           "fulfillmentChannel":{
              "value":"Amazon"            ## fulfilllmentChannel #1
           },
           "LandedPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.57"
              }
           },
           "ListingPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.57"
              }
           },
           "Shipping":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"0.00"
              }
           }
        },
        {
           "value":"\n                    ",
           "condition":{
              "value":"new"
           },
           "fulfillmentChannel":{
              "value":"Merchant"
           },
           "LandedPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.25"
              }
           },
           "ListingPrice":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"19.25"
              }
           },
           "Shipping":{
              "value":"\n                        ",
              "CurrencyCode":{
                 "value":"USD"
              },
              "Amount":{
                 "value":"0.00"
              }
           }
        }
     ]
  }
}

class TestStackOverflowQuestens(TestCase):
    
    def test_run1(self):
        x = MdlLowestPrices.parse_obj(data)
        for i in x.LowestPrices.LowestPrice:
               if (i.condition.value == "new" and i.fulfillmentChannel.value == "Amazon"):
                   print(i.ListingPrice.Amount.value)

【讨论】：

【解决方案3】：

这里有几种方法：

使用filter()


lowest_price = sku_multi_sku['Summary']['LowestPrices']['LowestPrice']

lowest_price_list = list(filter(lambda sku: sku['condition']['value'] == 'new' and sku['fulfillmentChannel']['value'] == 'Amazon'))

# if you are sure that there would be only one item with lowest_price, then
# CAUTION: One should, however, check for the None type
print(lowest_price_list[0]['ListingPrice']['Amount']['value']) # Output: 19.57

使用List Comprehension


lowest_price = sku_multi_sku['Summary']['LowestPrices']['LowestPrice']

lowest_price_list = [i for i in lowest_price if i['condition']['value'] == 'new' and i['fulfillmentChannel']['value'] == 'Amazon']

print(lowest_price_list[0]['ListingPrice']['Amount']['value'])
# Output: 19.57 --> With the same cautionary note as above

注意：filter() 转换为 list comprehension

【讨论】：