我如何使Python字典成员访问通过点“。”?
例如,我想写mydict.val而不是mydict['val']。
我还想以这种方式访问嵌套字典。例如
mydict.mydict2.val
会提到
mydict = { 'mydict2': { 'val': ... } }
我如何使Python字典成员访问通过点“。”?
例如,我想写mydict.val而不是mydict['val']。
我还想以这种方式访问嵌套字典。例如
mydict.mydict2.val
会提到
mydict = { 'mydict2': { 'val': ... } }
当前回答
如果你已经在使用pandas,你可以构造一个pandas Series或DataFrame,从中你可以通过点语法访问项目:
1级字典:
import pandas as pd
my_dictionary = pd.Series({
'key1': 'value1',
'key2': 'value2'
})
print(my_dictionary.key1)
# Output: value1
2级字典:
import pandas as pd
my_dictionary = pd.DataFrame({
'key1': {
'inner_key1': 'value1'
},
'key2': {
'inner_key2': 'value2'
}
})
print(my_dictionary.key1.inner_key1)
# Output: value1
请注意,这可能在规范化数据结构(其中每个字典条目都具有相同的结构)下工作得更好。在上面的第二个例子中,得到的DataFrame是:
key1 key2
inner_key1 value1 NaN
inner_key2 NaN value2
其他回答
你可以用我刚做的这个类来做。对于这个类,您可以像使用另一个字典(包括json序列化)一样使用Map对象,或者使用点表示法。希望对大家有所帮助:
class Map(dict):
"""
Example:
m = Map({'first_name': 'Eduardo'}, last_name='Pool', age=24, sports=['Soccer'])
"""
def __init__(self, *args, **kwargs):
super(Map, self).__init__(*args, **kwargs)
for arg in args:
if isinstance(arg, dict):
for k, v in arg.iteritems():
self[k] = v
if kwargs:
for k, v in kwargs.iteritems():
self[k] = v
def __getattr__(self, attr):
return self.get(attr)
def __setattr__(self, key, value):
self.__setitem__(key, value)
def __setitem__(self, key, value):
super(Map, self).__setitem__(key, value)
self.__dict__.update({key: value})
def __delattr__(self, item):
self.__delitem__(item)
def __delitem__(self, key):
super(Map, self).__delitem__(key)
del self.__dict__[key]
使用例子:
m = Map({'first_name': 'Eduardo'}, last_name='Pool', age=24, sports=['Soccer'])
# Add new key
m.new_key = 'Hello world!'
# Or
m['new_key'] = 'Hello world!'
print m.new_key
print m['new_key']
# Update values
m.new_key = 'Yay!'
# Or
m['new_key'] = 'Yay!'
# Delete key
del m.new_key
# Or
del m['new_key']
我喜欢Munch,它提供了很多方便的选项在点访问。
进口蒙克 Temp_1 = {'person': {' fname': 'senthil', 'lname': 'ramalingam'}} Dict_munch = munch.munchify(temp_1) dict_munch.person.fname
一个很微妙的解
class DotDict(dict):
__setattr__ = dict.__setitem__
__delattr__ = dict.__delitem__
def __getattr__(self, key):
def typer(candidate):
if isinstance(candidate, dict):
return DotDict(candidate)
if isinstance(candidate, str): # iterable but no need to iter
return candidate
try: # other iterable are processed as list
return [typer(item) for item in candidate]
except TypeError:
return candidate
return candidate
return typer(dict.get(self, key))
这是我对@derek73的回答。我用字典。__getitem__作为__getattr__,因此它仍然抛出KeyError,并且im重命名字典公共方法以“”前缀(“”包围导致特殊方法名称冲突,如__get__将被视为一个描述符方法)。无论如何,由于关键的dict基方法,您无法将键作为属性获得完全清晰的命名空间,因此解决方案并不完美,但您可以拥有键属性,如get, pop, items等。
class DotDictMeta(type):
def __new__(
cls,
name,
bases,
attrs,
rename_method=lambda n: f'__{n}__',
**custom_methods,
):
d = dict
attrs.update(
cls.get_hidden_or_renamed_methods(rename_method),
__getattr__=d.__getitem__,
__setattr__=d.__setitem__,
__delattr__=d.__delitem__,
**custom_methods,
)
return super().__new__(cls, name, bases, attrs)
def __init__(self, name, bases, attrs, **_):
super().__init__(name, bases, attrs)
@property
def attribute_error(self):
raise AttributeError
@classmethod
def get_hidden_or_renamed_methods(cls, rename_method=None):
public_methods = tuple(
i for i in dict.__dict__.items() if not i[0].startswith('__')
)
error = cls.attribute_error
hidden_methods = ((k, error) for k, v in public_methods)
yield from hidden_methods
if rename_method:
renamed_methods = ((rename_method(k), v) for k, v in public_methods)
yield from renamed_methods
class DotDict(dict, metaclass=DotDictMeta):
pass
你可以从DotDict命名空间中删除dict方法,并继续使用dict类方法,当你想操作其他dict实例并希望使用相同的方法而不需要额外检查它是否为DotDict时,它也很有用。
dct = dict(a=1)
dot_dct = DotDict(b=2)
foo = {c: i for i, c in enumerate('xyz')}
for d in (dct, dot_dct):
# you would have to use dct.update and dot_dct.__update methods
dict.update(d, foo)
assert dict.get(dot, 'foo', 0) is 0
这是我从很久以前的一个项目里挖出来的。它可能还可以再优化一点,但就是这样了。
class DotNotation(dict):
__setattr__= dict.__setitem__
__delattr__= dict.__delitem__
def __init__(self, data):
if isinstance(data, str):
data = json.loads(data)
for name, value in data.items():
setattr(self, name, self._wrap(value))
def __getattr__(self, attr):
def _traverse(obj, attr):
if self._is_indexable(obj):
try:
return obj[int(attr)]
except:
return None
elif isinstance(obj, dict):
return obj.get(attr, None)
else:
return attr
if '.' in attr:
return reduce(_traverse, attr.split('.'), self)
return self.get(attr, None)
def _wrap(self, value):
if self._is_indexable(value):
# (!) recursive (!)
return type(value)([self._wrap(v) for v in value])
elif isinstance(value, dict):
return DotNotation(value)
else:
return value
@staticmethod
def _is_indexable(obj):
return isinstance(obj, (tuple, list, set, frozenset))
if __name__ == "__main__":
test_dict = {
"dimensions": {
"length": "112",
"width": "103",
"height": "42"
},
"meta_data": [
{
"id": 11089769,
"key": "imported_gallery_files",
"value": [
"https://example.com/wp-content/uploads/2019/09/unnamed-3.jpg",
"https://example.com/wp-content/uploads/2019/09/unnamed-2.jpg",
"https://example.com/wp-content/uploads/2019/09/unnamed-4.jpg"
]
}
]
}
dotted_dict = DotNotation(test_dict)
print(dotted_dict.dimensions.length) # => '112'
print(getattr(dotted_dict, 'dimensions.length')) # => '112'
print(dotted_dict.meta_data[0].key) # => 'imported_gallery_files'
print(getattr(dotted_dict, 'meta_data.0.key')) # => 'imported_gallery_files'
print(dotted_dict.meta_data[0].value) # => ['link1','link2','link2']
print(getattr(dotted_dict, 'meta_data.0.value')) # => ['link1','link2','link3']
print(dotted_dict.meta_data[0].value[2]) # => 'link3'
print(getattr(dotted_dict, 'meta_data.0.value.2')) # => 'link3'