我使用的一个解决方案类似于double get，但具有使用if else逻辑避免TypeError的额外能力:

    value = example_dict['key1']['key2'] if example_dict.get('key1') and example_dict['key1'].get('key2') else default_value

然而，字典嵌套越多，这就变得越麻烦。

虽然reduce方法简洁而简短，但我认为简单的循环更容易理解。我还包含了一个默认参数。

def deep_get(_dict, keys, default=None):
    for key in keys:
        if isinstance(_dict, dict):
            _dict = _dict.get(key, default)
        else:
            return default
    return _dict

作为理解reduce一行程序如何工作的练习，我执行了以下操作。但最终循环方法对我来说似乎更直观。

def deep_get(_dict, keys, default=None):

    def _reducer(d, key):
        if isinstance(d, dict):
            return d.get(key, default)
        return default

    return reduce(_reducer, keys, _dict)

使用

nested = {'a': {'b': {'c': 42}}}

print deep_get(nested, ['a', 'b'])
print deep_get(nested, ['a', 'b', 'z', 'z'], default='missing')

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)

下面是一个基于unutbu函数答案的解决方案:

Python命名指南 默认值作为参数 不用try，只是检查key是否在object上

def safe_get(dictionary, *keys, default=None):
    for key in keys:
        if key not in dictionary:
            return default
        dictionary = dictionary[key]
    return dictionary

我使用的一个解决方案类似于double get，但具有使用if else逻辑避免TypeError的额外能力:

    value = example_dict['key1']['key2'] if example_dict.get('key1') and example_dict['key1'].get('key2') else default_value

然而，字典嵌套越多，这就变得越麻烦。

已经有很多很好的答案，但我已经提出了一个类似于JavaScript领域的lodash get的函数，它也支持通过索引进入列表:

def get(value, keys, default_value = None):
'''
    Useful for reaching into nested JSON like data
    Inspired by JavaScript lodash get and Clojure get-in etc.
'''
  if value is None or keys is None:
      return None
  path = keys.split('.') if isinstance(keys, str) else keys
  result = value
  def valid_index(key):
      return re.match('^([1-9][0-9]*|[0-9])$', key) and int(key) >= 0
  def is_dict_like(v):
      return hasattr(v, '__getitem__') and hasattr(v, '__contains__')
  for key in path:
      if isinstance(result, list) and valid_index(key) and int(key) < len(result):
          result = result[int(key)] if int(key) < len(result) else None
      elif is_dict_like(result) and key in result:
          result = result[key]
      else:
          result = default_value
          break
  return result

def test_get():
  assert get(None, ['foo']) == None
  assert get({'foo': 1}, None) == None
  assert get(None, None) == None
  assert get({'foo': 1}, []) == {'foo': 1}
  assert get({'foo': 1}, ['foo']) == 1
  assert get({'foo': 1}, ['bar']) == None
  assert get({'foo': 1}, ['bar'], 'the default') == 'the default'
  assert get({'foo': {'bar': 'hello'}}, ['foo', 'bar']) == 'hello'
  assert get({'foo': {'bar': 'hello'}}, 'foo.bar') == 'hello'
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.0.bar') == 'hello'
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.1') == None
  assert get({'foo': [{'bar': 'hello'}]}, 'foo.1.bar') == None
  assert get(['foo', 'bar'], '1') == 'bar'
  assert get(['foo', 'bar'], '2') == None