Python中的嵌套字典迭代

我有一个字典，它有几个选项键值对，然后有一个sub_dict属性，它是一个具有相同属性的更多字典的列表，这些字典也有可能一直有sub_dict

在python中，我将其分解并单独处理，一次修改一个，并希望将修改后的系统与整个系统重新组合。但是我不知道如何迭代它

{base_system: {
name: "root",
description: "data dictionary",
common_data: {},
other_data: {},
more_data: {},
sub_systems: [
    {
        base_system: {
        name: "another system",
        description: "inherits from top level",
        sub_systems: [
            {
                base_system: {}
            },
            {
                base_system: {}
            }
        ]
        }
    },
    {
        base_system: {
            name: "one more system",
            description: "inheriting again",
            sub_systems: [
            {
                base_system: {
                name: "child system",
                description: "no kids here",
                other_data: {},
                more_data: {}
                }
            },
            {
                base_system: {
                name: "kid system",
                description: "no children here"
                }
            }
            ]
        }
    }
]
}

}

我想做这样的事情，但我不知道该怎么做才能使它递归

#Have some recursive function to dig through the overall dictionary then test:
if the_dict_object["space_system"]["name"] == changed_json_system["space_system"]["name"]:
  #then when it passes that if statement I can just set
  the_dict_object = changed_json_system

但是我不知道如何迭代嵌套字典，并且仍然保留整个对象。

您可以使用instanceof（）方法检查某个对象是否为dict，如果为true，则可以使代码迭代该dict。在这种情况下，我将执行递归

def read_dict(some_dictionary):
    for key, value in some_dictionary:

        if isinstance(value, dict): 
            # if value is another dict, iterate through the key,value pairs in value
            read_dict(value) 
        elif isinstance(value, list):
            # if value is a list, add your own code to iterate through a list
            pass
        else:
            #not a dict, do what you needed to do eg:
            print 'value of %s is %s' % (key, value) 

read_dict(the_dict_object)

---

下面是递归遍历dict结构的示例代码。对于本例，它将使用说明的大写字母替换说明

_DESC = "description"
_BASESYS = "base_system"
_SUBSYS = "sub_systems"

def uppercase_desc(system_info):
    """
    Change a system object such that the description is in upper-case.
    """
    if _BASESYS not in system_info:
        return

    subd = system_info[_BASESYS]
    if _DESC in subd:
        subd[_DESC] = subd[_DESC].upper()
    if _SUBSYS not in subd:
        return
    for d in subd[_SUBSYS]:
        uppercase_desc(d)

if __name__ == "__main__":
    import json
    with open("data.json", "rt") as f:
        s = f.read()
    system_info = json.loads(s)

    uppercase_desc(system_info)
    s = json.dumps(system_info, indent=4, sort_keys=True)
    print(s)

上面的代码修改了字典。这是一个有点棘手，但不是坏的，做一个副本，你去，并返回副本。这可能更可取

这里唯一棘手的部分是代码默认使用

copy.deepcopy（）

。因为我们不知道字典里可能有什么，我们想返回一个副本，所以我们可以调用

copy.deepcopy（）

；它将在像

3

（值为3的整数对象）这样的简单对象上正常工作并做正确的事情

另外，您发布的示例数据不是有效的JSON。我通过在键周围加上双引号对其进行了修改，并用漂亮的缩进打印了它，以使我的测试文件

data.json

。这是：

{
    "base_system": {
        "name": "root", 
        "description": "data dictionary", 
        "more_data": {}, 
        "common_data": {}, 
        "sub_systems": [
            {
                "base_system": {
                    "name": "another system", 
                    "sub_systems": [
                        {
                            "base_system": {}
                        }, 
                        {
                            "base_system": {}
                        }
                    ], 
                    "description": "inherits from top level"
                }
            }, 
            {
                "base_system": {
                    "name": "one more system", 
                    "sub_systems": [
                        {
                            "base_system": {
                                "more_data": {}, 
                                "other_data": {}, 
                                "name": "child system", 
                                "description": "no kids here"
                            }
                        }, 
                        {
                            "base_system": {
                                "name": "kid system", 
                                "description": "no children here"
                            }
                        }
                    ], 
                    "description": "inheriting again"
                }
            }
        ], 
        "other_data": {}
    }
}

---

你想比较所有的值吗？我想检查一下我刚刚处理的系统/子系统的名称，看看它是否与我当前在字典中看到的名称匹配，如果匹配，我想用我刚刚处理的子系统替换该子系统。你可能也会喜欢这样：如果我这样做，将一个或两个递归更改为函数它改变了最初的一个？听起来你对python变量的作用域不太熟悉。我建议您尝试执行此命令，添加一些打印语句并进行调试。你会发现你的答案是这样的？你的意思是“存在”吗？我错了，是的，存在：）谢谢你的纠正。

{
    "base_system": {
        "name": "root", 
        "description": "data dictionary", 
        "more_data": {}, 
        "common_data": {}, 
        "sub_systems": [
            {
                "base_system": {
                    "name": "another system", 
                    "sub_systems": [
                        {
                            "base_system": {}
                        }, 
                        {
                            "base_system": {}
                        }
                    ], 
                    "description": "inherits from top level"
                }
            }, 
            {
                "base_system": {
                    "name": "one more system", 
                    "sub_systems": [
                        {
                            "base_system": {
                                "more_data": {}, 
                                "other_data": {}, 
                                "name": "child system", 
                                "description": "no kids here"
                            }
                        }, 
                        {
                            "base_system": {
                                "name": "kid system", 
                                "description": "no children here"
                            }
                        }
                    ], 
                    "description": "inheriting again"
                }
            }
        ], 
        "other_data": {}
    }
}