字典
常用操作：
索引
新增
删除
键、值、键值对
循环
长度
字典由键值对组成，由一个键（名称）和 一个值组成，与列表和元组不同的是里面的元素是有键的（名称）
所以当要打印字典时，打印字典变量加[键]即可
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a["ls"])
9 #打印出 2 打印出了ls键的值
创建字典
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {"zhs":"1", "ls":"2", "ww":"3"}
4 #或者
5 a = dict({"zhs":"1", "ls":"2", "ww":"3"})
6 #或者
7 a = {
8 "zhs":"1",
9 "ls":"2",
10 "ww":"3"
11 }
12 #一般采用第三中，更容易读
索引
打印字典变量加[要打印的键]
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a["ls"])
9 print(a["ww"])
10 #打印出 2 3 打印出了ls和ww键的值
for循环
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 for b in a:
9 print(b)
10 #打印出 ww zhs ls 默认循环出的是字典的键
11
12 a = {
13 "zhs":"1",
14 "ls":"2",
15 "ww":"3"
16 }
17 for b in a:
18 print(a[b])
19 #打印出 3 1 2 要打印字典变量加上[自定义循环变量，也就是键]才能打印出值
keys(self)
"""(获取字典的键)"""：返回一个字典的键列表
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a.keys())
9 #打印出 [‘ww‘, ‘zhs‘, ‘ls‘] 返回字典键列表
values(self)
"""(获取字典的值)"""：返回一个字典的值列表
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a.values())
9 #打印出 [‘3‘, ‘1‘, ‘2‘] 返回字典值列表
items(self)
"""(获取字典里的键和值)"""：返回一个字典的键和值列表加元组
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a.items())
9 #打印出 [(‘ww‘, ‘3‘), (‘zhs‘, ‘1‘), (‘ls‘, ‘2‘)] 返回字典里的键和值列表加元组
(keys：获取键) (values：获取值) (items：获取键和值) 结合for循环
(keys：获取键)结合for循环
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 for b in a.keys():
9 print(b)
10 #打印出 ww zhs ls 循环出了字典的键
(values：获取值)结合for循环
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 for b in a.values():
9 print(b)
10 #打印出 3 1 2 循环出了字典的值
(items：获取键和值)结合for循环
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 for k, v in a.items(): #因为items()获取的键和值，所以循环里要自定义两个变量分别代表键和值
9 print(k)
10 print(v)
11 #打印出 ww 3 zhs 1 ls 2 循环出了字典的键和值
clear(self)
"""(清除字典里的所有内容)"""
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 a.clear()
9 print(a)
10 #打印出 {} 字典里是空的
get(self, k, d=None)（推荐使用）
""" (根据key(键)获取值，如果key(键)不存在可以指定默认值 )"""：如果键后面指定了默认值，键存在就获取键自身的值，如果键不存在就获取默认值
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a.get("ls"))
9 #打印出 2 输出指定键的值
10
11 a = {
12 "zhs":"1",
13 "ls":"2",
14 "ww":"3"
15 }
16 print(a.get("xyz","123")) #xyz键不存在，就获取默认值123
17 #打印出 123 输出指定键的值,如果指定键不存在就输出默认值
has_key(self, k)
注意：python3版本以上已经取消了
""" （：键）key：键，名称 """：返回真或者假
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 print(a.has_key("ls"))
9 #打印出 True 返回真说明字典里有ls这个键
判断字典里是否有某个key键：返回真或者假
也可以判断字典里是否有某个值
注意：python3版本以上使用这个方法替代已经取消的has_key
格式："要判断的键" in 字典变量.keys()
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 b = "ls" in a.keys()
9 print(b)
10 #打印出 True 返回真说明字典里有ls这个键
11
12 a = {
13 "zhs":"1",
14 "ls":"2",
15 "ww":"3"
16 }
17 b = "2" in a.values()
18 print(b)
19 #打印出 True 返回真说明字典里有2这个值
update(self, E=None, **F)
""" （追加更新）"""要追加更新的变量
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 b = {
9 "z":"4",
10 "l":"5",
11 "w":"6"
12 }
13 a.update(b)
14 print(a)
15 #打印输出 {‘ww‘: ‘3‘, ‘zhs‘: ‘1‘, ‘ls‘: ‘2‘, ‘w‘: ‘6‘, ‘z‘: ‘4‘, ‘l‘: ‘5‘} 将b字典追加更新到了a字典
删除字典里的元素
格式：del 字典变量.[要删除的元素键]
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = {
4 "zhs":"1",
5 "ls":"2",
6 "ww":"3"
7 }
8 del a["ls"]
9 print(a)
10 #打印输出 {‘ww‘: ‘3‘, ‘zhs‘: ‘1‘} 删除了ls键这个元素
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__
""" 清除内容 """
""" D.clear() -> None. Remove all items from D. """
pass
def copy(self): # real signature unknown; restored from __doc__
""" 浅拷贝 """
""" D.copy() -> a shallow copy of D """
pass
@staticmethod # known case
def fromkeys(S, v=None): # real signature unknown; restored from __doc__
"""
dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.
v defaults to None.
"""
pass
def get(self, k, d=None): # real signature unknown; restored from __doc__
""" 根据key获取值，d是默认值 """
""" D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """
pass
def has_key(self, k): # real signature unknown; restored from __doc__
""" 是否有key """
""" D.has_key(k) -> True if D has a key k, else False """
return False
def items(self): # real signature unknown; restored from __doc__
""" 所有项的列表形式 """
""" D.items() -> list of D‘s (key, value) pairs, as 2-tuples """
return []
def iteritems(self): # real signature unknown; restored from __doc__
""" 项可迭代 """
""" D.iteritems() -> an iterator over the (key, value) items of D """
pass
def iterkeys(self): # real signature unknown; restored from __doc__
""" key可迭代 """
""" D.iterkeys() -> an iterator over the keys of D """
pass
def itervalues(self): # real signature unknown; restored from __doc__
""" value可迭代 """
""" D.itervalues() -> an iterator over the values of D """
pass
def keys(self): # real signature unknown; restored from __doc__
""" 所有的key列表 """
""" D.keys() -> list of D‘s keys """
return []
def pop(self, k, d=None): # real signature unknown; restored from __doc__
""" 获取并在字典中移除 """
"""
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__
""" 获取并在字典中移除 """
"""
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__
""" 如果key不存在，则创建，如果存在，则返回已存在的值且不修改 """
""" 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
""" 更新
{‘name‘:‘alex‘, ‘age‘: 18000}
[(‘name‘,‘sbsbsb‘),]
"""
"""
D.update([E, ]**F) -> None. Update D from dict/iterable E and F.
If E present and has a .keys() method, does: for k in E: D[k] = E[k]
If E present and lacks .keys() method, 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__
""" 所有的值 """
""" D.values() -> list of D‘s values """
return []
def viewitems(self): # real signature unknown; restored from __doc__
""" 所有项，只是将内容保存至view对象中 """
""" D.viewitems() -> a set-like object providing a view on D‘s items """
pass
def viewkeys(self): # real signature unknown; restored from __doc__
""" D.viewkeys() -> a set-like object providing a view on D‘s keys """
pass
def viewvalues(self): # real signature unknown; restored from __doc__
""" D.viewvalues() -> an object providing a view on D‘s values """
pass
def __cmp__(self, y): # real signature unknown; restored from __doc__
""" x.__cmp__(y) <==> cmp(x,y) """
pass
def __contains__(self, k): # real signature unknown; restored from __doc__
""" D.__contains__(k) -> True if D has a key k, else False """
return False
def __delitem__(self, y): # real signature unknown; restored from __doc__
""" x.__delitem__(y) <==> del x[y] """
pass
def __eq__(self, y): # real signature unknown; restored from __doc__
""" x.__eq__(y) <==> x==y """
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__(‘name‘) <==> x.name """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __ge__(self, y): # real signature unknown; restored from __doc__
""" x.__ge__(y) <==> x>=y """
pass
def __gt__(self, y): # real signature unknown; restored from __doc__
""" x.__gt__(y) <==> x>y """
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): # real signature unknown; restored from __doc__
""" x.__iter__() <==> iter(x) """
pass
def __len__(self): # real signature unknown; restored from __doc__
""" x.__len__() <==> len(x) """
pass
def __le__(self, y): # real signature unknown; restored from __doc__
""" x.__le__(y) <==> x<=y """
pass
def __lt__(self, y): # real signature unknown; restored from __doc__
""" x.__lt__(y) <==> x<y """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __ne__(self, y): # real signature unknown; restored from __doc__
""" x.__ne__(y) <==> x!=y """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __setitem__(self, i, y): # real signature unknown; restored from __doc__
""" x.__setitem__(i, y) <==> x[i]=y """
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" D.__sizeof__() -> size of D in memory, in bytes """
pass
__hash__ = None
dict
时间： 2024-10-03 04:15:12