字典由多個鍵與其對應的值構成的對組成，是另一種可變容器模型，且可儲存任意型別物件。字典的每個鍵值用冒號(:)分割，每個對之間用逗號(,)分割，整個字典包括在花括號({})中。
注：字典中的鍵是唯一的（其他型別的對映也是如此），而值不是唯一的。
字典類似於你通過聯絡人名字查詢地址和聯絡人詳細情況的地址簿.即，我們把鍵（名字）和值（詳細情況）聯絡在一起。注意，鍵必須是唯一的，字典中的鍵/值對是沒有順序的(字典是無序的)。如果想要一個特定的順序，那麼應該在使用前自己對它們排序。字典是dict類的例項/物件。
字典是python中唯一的內建對映型別
1.dict 函式
使用dict 函式，通過其他對映（其他字典或鍵-值）這樣的序列對建立字典
items = [("name","zhangsan"),("age",28),("job","educator")]
D = dict(items)
print (D)
print (type(D))2. 字典的格式化字串
一個電話本為例子的字典程式碼（引用格式化字串）
phonebook = {
"zhangsan":{
"phone":"01012345",
"addr":"tianhedong 32 hao",
},
"lisi":{
"phone":"02023456",
"addr":"huangpunan 54 hao",
},
"zhaowu":{
"phone":"03034567",
"addr":"tianhebei 17 hao",
},
"xiesen":{
"phone":"06054321",
"addr":"tianhexi 12 hao",
},
}
labels ={
"phone":"phone numbers",
"addr":"address"
}
name = input ("please input your name:")
if "request" == "p" :key = "phone"
if "request" == "a" :key = "addr"
if name in phonebook :
print ("%s's %s is %s." %(name, labels[key], phonebook[name][key]))字典的方法
1. clear
clear 清除字典的所有項.類似list.sort ,無返回值
D = {}
D["name"] = "xieshengsen"
D["age"] = 25
print (D)
returned_value = D.clear()
print (D)
print (returned_value)2. copy
copy 返回一個具有相同鍵值對的新字典（淺複製）
Q = {"username":"admin","machines":["foo","bar","baz"]}
QQ = Q.copy()
print (Q)
print (QQ)
QQ["username"] = "Administrator"
QQ["machines"].remove("bar")
print(Q)
print(QQ)深複製
form copy import deepcopy
import copy
d = {}
d["names"] = ["hello","world"]
print (d)
dd = copy.copy(d)
dc = copy.deepcopy(d)
d["names"].append("haha")
print (d)
print (dd)
print(dc)3. fromkeys
fromkeys 使用給定的鍵建立新的字典，每個鍵預設對應的值為none
print({}.fromkeys(["name","age"])) # none 作為預設值
print(dict.fromkeys(["name","age"]),"(unknown)") # 修改unknown 為預設值4. get
get 更寬鬆的訪問字典項的方法（一般來說，如果訪問字典中不存在的項時會出錯，使用get訪問不會出現錯誤）
AA = {}
# print (AA["name"]) # 出現錯誤
print (AA.get("name")) # 鍵值不存在,輸出結果None
AA["name"]= "xieshengsen"
print (AA.get("name"))5. items 和iteritems
items 方法將所有的字典項以列表方式返回，這些列表項中的每一項都是來自（鍵-值）。但是項在返回時並沒有特殊的順序。
II = {"title": "python web site","url":"https://www.python.org","spam":0}
print (II.items())iteritems 會返回一個迭代器 而不是列表（python3 已經沒有iteritems 這個方法）
6. keys 和iterkeys
keys 方法將字典的鍵以列表形式返回，而iterkeys 則返回針對鍵的迭代器
7. pop
pop 方法用來獲取對應於給定的鍵的值，然後將這個鍵-值對從字典中移除
dd = {"hh":1,"yy":2,"vv":3,"gg":4}
print (dd.pop("hh"))
print (dd)8. popitem
popitem 方法類似於list.pop，後者會彈出列表的最後一個元素。但，popitem彈出隨機項，因為字典沒有“最後元素”的概念（字典是無序的）.
p = {"url":"https://www.python.org/","spam":0,"title":"python web site"}
print (p.popitem())
print (p)9. setdefault
setdefault 類似於get方法，能夠獲得與給定鍵相關聯的值，setdefault還能在字典中不含有給定鍵的情況下設定相應的鍵值
set = {}
print (set.setdefault("name","N/A"))
print (set)
set["name"] = "zhangsan"
print (set.setdefault("name","N/A"))
print (set)當鍵不存在時，setdefault 返回預設值並相應的更新字典，如果鍵存在，返回其相應值，但不改變字典。
10. update
update 方法是利用一個字典項更新另外一個字典.
up = {"color":"red","number":"1234","animal":"Bear","Fruits":"apples"}
da = {"Stationery":"book","food":"milk"}
up.update(da)
print (up)提供的字典的項會被新增到舊字典中，相同的鍵會被覆蓋
11. values
values 方法以列表的形式返回字典的值（itervalues 返回值的迭代器,python3 沒有）,與返回值的列表不同的是，返回值列表中可以包含重複的元素。
valu = {}
valu[1]=1
valu[2]=2
valu[3]=3
valu[4]=1
print (valu.values())字典dict官方解析
class dict(object):
"""
dict() -> new empty dictionary
dict(mapping) -> new dictionary initialized from a mapping object's
(key, value) pairs
dict(iterable) -> new dictionary initialized as if via:
d = {}
for k, v in iterable:
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)
"""
def clear(self): # real signature unknown; restored from __doc__
""" D.clear() -> None. Remove all items from D. """
pass
def copy(self): # real signature unknown; restored from __doc__
""" D.copy() -> a shallow copy of D """
pass
@staticmethod # known case
def fromkeys(*args, **kwargs): # real signature unknown
""" Returns a new dict with keys from iterable and values equal to value. """
pass
def get(self, k, d=None): # real signature unknown; restored from __doc__
""" D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """
pass
def items(self): # real signature unknown; restored from __doc__
""" D.items() -> a set-like object providing a view on D's items """
pass
def keys(self): # real signature unknown; restored from __doc__
""" D.keys() -> a set-like object providing a view on D's keys """
pass
def pop(self, k, d=None): # real signature unknown; restored from __doc__
"""
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
"""
pass
def popitem(self): # real signature unknown; restored from __doc__
"""
D.popitem() -> (k, v), remove and return some (key, value) pair as a
2-tuple; but raise KeyError if D is empty.
"""
pass
def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
""" D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
pass
def update(self, E=None, **F): # known special case of dict.update
"""
D.update([E, ]**F) -> None. Update D from dict/iterable E and F.
If E is present and has a .keys() method, then does: for k in E: D[k] = E[k]
If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v
In either case, this is followed by: for k in F: D[k] = F[k]
"""
pass
def values(self): # real signature unknown; restored from __doc__
""" D.values() -> an object providing a view on D's values """
pass
def __contains__(self, *args, **kwargs): # real signature unknown
""" True if D has a key k, else False. """
pass
def __delitem__(self, *args, **kwargs): # real signature unknown
""" Delete self[key]. """
pass
def __eq__(self, *args, **kwargs): # real signature unknown
""" Return self==value. """
pass
def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __ge__(self, *args, **kwargs): # real signature unknown
""" Return self>=value. """
pass
def __gt__(self, *args, **kwargs): # real signature unknown
""" Return self>value. """
pass
def __init__(self, seq=None, **kwargs): # known special case of dict.__init__
"""
dict() -> new empty dictionary
dict(mapping) -> new dictionary initialized from a mapping object's
(key, value) pairs
dict(iterable) -> new dictionary initialized as if via:
d = {}
for k, v in iterable:
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)
# (copied from class doc)
"""
pass
def __iter__(self, *args, **kwargs): # real signature unknown
""" Implement iter(self). """
pass
def __len__(self, *args, **kwargs): # real signature unknown
""" Return len(self). """
pass
def __le__(self, *args, **kwargs): # real signature unknown
""" Return self<=value. """
pass
def __lt__(self, *args, **kwargs): # real signature unknown
""" Return self<value. """
pass
@staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
""" Create and return a new object. See help(type) for accurate signature. """
pass
def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass
def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass
def __setitem__(self, *args, **kwargs): # real signature unknown
""" Set self[key] to value. """
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" D.__sizeof__() -> size of D in memory, in bytes """
pass
__hash__ = None