我有一本嵌套的字典。是否只有一种方法可以安全地传递价值观?

try:
    example_dict['key1']['key2']
except KeyError:
    pass

或者python有一个类似get()的方法用于嵌套字典?


当前回答

减少方法的改进很少,使其与列表一起工作。也使用数据路径作为字符串除以点,而不是数组。

def deep_get(dictionary, path):
    keys = path.split('.')
    return reduce(lambda d, key: d[int(key)] if isinstance(d, list) else d.get(key) if d else None, keys, dictionary)

其他回答

根据Yoav的回答,一个更安全的方法是:

def deep_get(dictionary, *keys):
    return reduce(lambda d, key: d.get(key, None) if isinstance(d, dict) else None, keys, dictionary)

我已经编写了一个deepextract包,它完全符合您的要求:https://github.com/ya332/deepextract 你可以这样做

from deepextract import deepextract
# Demo: deepextract.extract_key(obj, key)
deeply_nested_dict = {
    "items": {
        "item": {
            "id": {
                "type": {
                    "donut": {
                        "name": {
                            "batters": {
                                "my_target_key": "my_target_value"
                            }
                        }
                    }
                }
            }
        }
    }
}
print(deepextract.extract_key(deeply_nested_dict, "my_target_key") == "my_target_value")

返回

True

还有一个相同功能的函数,也返回一个布尔值来表示是否找到键,并处理一些意想不到的错误。

'''
json : json to extract value from if exists
path : details.detail.first_name
            empty path represents root

returns a tuple (boolean, object)
        boolean : True if path exists, otherwise False
        object : the object if path exists otherwise None

'''
def get_json_value_at_path(json, path=None, default=None):

    if not bool(path):
        return True, json
    if type(json) is not dict :
        raise ValueError(f'json={json}, path={path} not supported, json must be a dict')
    if type(path) is not str and type(path) is not list:
        raise ValueError(f'path format {path} not supported, path can be a list of strings like [x,y,z] or a string like x.y.z')

    if type(path) is str:
        path = path.strip('.').split('.')
    key = path[0]
    if key in json.keys():
        return get_json_value_at_path(json[key], path[1:], default)
    else:
        return False, default

使用示例:

my_json = {'details' : {'first_name' : 'holla', 'last_name' : 'holla'}}
print(get_json_value_at_path(my_json, 'details.first_name', ''))
print(get_json_value_at_path(my_json, 'details.phone', ''))

(真的,大声叫) (假的,”)

你可以使用pydash:

import pydash as _  #NOTE require `pip install pydash`

_.get(example_dict, 'key1.key2', default='Default')

https://pydash.readthedocs.io/en/latest/api.html

我稍微改变了一下答案。我添加了检查,如果我们使用列表与数字。 所以现在我们可以用任何一种方法。deep_get(allTemp,[0],{})或deep_get(getMinimalTemp, [0, minimalTemperatureKey], 26)等

def deep_get(_dict, keys, default=None):
    def _reducer(d, key):
        if isinstance(d, dict):
            return d.get(key, default)
        if isinstance(d, list):
            return d[key] if len(d) > 0 else default
        return default
    return reduce(_reducer, keys, _dict)