dictionary

日常用法：

__class__      dict() -> new empty dictionary. dict(mapping) -> new dictionary initialized from a mapping object's (key, value) pairs. dict(seq) -> new dictionary initialized as if via: d = {} for k, v in seq: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2)
__cmp__        x.__cmp__(y) <==> cmp(x,y)
__contains__     D.__contains__(k) -> True if D has a key k, else False
__delattr__       x.__delattr__('name') <==> del x.name
__delitem__       x.__delitem__(y) <==> del x[y]
__eq__     x.__eq__(y) <==> x==y
__ge__     x.__ge__(y) <==> x>=y
__getattribute__        x.__getattribute__('name') <==> x.name
__getitem__       x.__getitem__(y) <==> x[y]
__gt__     x.__gt__(y) <==> x>y
__hash__   x.__hash__() <==> hash(x)
__init__   x.__init__(...) initializes x; see x.__class__.__doc__ for signature
__iter__   x.__iter__() <==> iter(x)
__le__     x.__le__(y) <==> x<=y
__len__    x.__len__() <==> len(x)
__lt__     x.__lt__(y) <==> x__ne__     x.__ne__(y) <==> x!=y
__new__    T.__new__(S, ...) -> a new object with type S, a subtype of T
__reduce__       helper for pickle
__reduce_ex__       helper for pickle
__repr__         x.__repr__() <==> repr(x)
__setattr__        x.__setattr__('name', value) <==> x.name = value
__setitem__         x.__setitem__(i, y) <==> x[i]=y
__str__         x.__str__() <==> str(x)
clear      D.clear() -> None. Remove all items from D.
copy       D.copy() -> a shallow copy of D
fromkeys   dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v. v defaults to None.
get        D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None.
has_key    D.has_key(k) -> True if D has a key k, else False
items      D.items() -> list of D's (key, value) pairs, as 2-tuples
iteritems  D.iteritems() -> an iterator over the (key, value) items of D
iterkeys   D.iterkeys() -> an iterator over the keys of D
itervalues D.itervalues() -> an iterator over the values of D
keys       D.keys() -> list of D's keys
pop        D.pop(k[,d]) -> v, remove specified key and return the corresponding value If key is not found, d is returned if given, otherwise KeyError is raised
popitem    D.popitem() -> (k, v), remove and return some (key, value) pair as a 2-tuple; but raise KeyError if D is empty
setdefault D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D
update     D.update(E, **F) -> None. Update D from E and F: for k in E: D[k] = E[k] (if E has keys else: for (k, v) in E: D[k] = v) then: for k in F: D[k] = F[k]
values     D.values() -> list of D's values

从 dictionary 中删除元素

>>> d
{'server': 'mpilgrim', 'uid': 'sa', 'database': 'master',
42: 'douglas', 'retrycount': 3}
>>> del d[42]
>>> d
{'server': 'mpilgrim', 'uid': 'sa', 'database': 'master', 'retrycount': 3}
>>> d.clear()
>>> d
{}

del 允许您使用 key 从一个 dictionary 中删除独立的元素。

clear 从一个 dictionary 中清除所有元素。注意空的大括号集合表示一个没有元素的 dictionary。

keys，values，items函数

>>> params = {"server":"mpilgrim", "database":"master", "uid":"sa", "pwd":"secret"}
>>> params.keys()
['server', 'uid', 'database', 'pwd']
>>> params.values()
['mpilgrim', 'sa', 'master', 'secret']
>>> params.items()
[('server', 'mpilgrim'), ('uid', 'sa'), ('database', 'master'), ('pwd', 'secret')]

Dictionary 的 keys 方法返回一个所有键的 list。这个 list 没按 dictionary 定义的顺序输出 (记住, 元素在 dictionary 中是无序的), 但它是一个 list。

values 方法返回一个所有值的 list。这个 list 以 keys 返回的 list 顺序输出, 所以对于所有的 n, params.values()[n] == params[params.keys()[n]] 。

items 方法返回一个形如 (key, value) 的 tuple 的 list。这个 list 包括 dictionary 中所有的数据。