[知识点备忘] 第037讲：字典（中）

>>> x = {"吕布","关羽"}
>>> type(x)
<class 'set'>
>>> y = {"吕布":"小小布","关羽":"小关关"}
>>> type(y)
<class 'dict'>
>>> y = ["吕布"]
>>> y = {"吕布":"小小布","关羽":"小关关"}
>>> y["吕布"]
'小小布'
>>> y["刘备"] = "小备备"
>>> y
{'吕布': '小小布', '关羽': '小关关', '刘备': '小备备'}
>>> a = {"吕布":"小小布","关羽":"小关关","刘备":"小备备"}
>>> b = dic(吕布="小小布",关羽="小关关",刘备="小备备")
Traceback (most recent call last):
  File "<pyshell#10>", line 1, in <module>
    b = dic(吕布="小小布",关羽="小关关",刘备="小备备")
NameError: name 'dic' is not defined
>>> b = dict(吕布="小小布",关羽="小关关",刘备="小备备")
>>> c = dict([("吕布","小小布"),("关羽","小关关"),("刘备","小备备")])
>>> d = dict({"吕布":"小小布","关羽":"小关关","刘备":"小备备"})
>>> e = dict({"吕布":"小小布","关羽":"小关关"},刘备="小备备")
>>> f = dict(zip(["吕布","关羽","刘备"],["小小布","小关关","小备备"]))
>>> a == b == c == d == e == f
True
>>> ["fromkeys(iterable[,values]) 可以使用 iterable 参数指定的可迭代对象来创建一个新的字典，并将所有的值初始化为 values 参数指定的值"]
['fromkeys(iterable[,values]) 可以使用 iterable 参数指定的可迭代对象来创建一个新的字典，并将所有的值初始化为 values 参数指定的值']
>>> d = dict.fromkeys("Fish",250)
>>> d
{'F': 250, 'i': 250, 's': 250, 'h': 250}
>>> d["F"] = 70
>>> d
{'F': 70, 'i': 250, 's': 250, 'h': 250}
>>> d["C"] = 67
>>> d
{'F': 70, 'i': 250, 's': 250, 'h': 250, 'C': 67}
>>> ["删除字典中指定的元素---pop(key[,default])"]
['删除字典中指定的元素---pop(key[,default])']
>>> d.pop("s")
250
>>> d
{'F': 70, 'i': 250, 'h': 250, 'C': 67}
>>> d.pop("狗")
Traceback (most recent call last):
  File "<pyshell#27>", line 1, in <module>
    d.pop("狗")
KeyError: '狗'
>>> d.pop("狗","没有")
'没有'
>>> d.popitem()
('C', 67)
>>> d
{'F': 70, 'i': 250, 'h': 250}
>>> ["d.popitem()，默认删除字典中最后一组"]
['d.popitem()，默认删除字典中最后一组']
>>> del d["i"]
>>> d
{'F': 70, 'h': 250}
>>> del d
>>> d
Traceback (most recent call last):
  File "<pyshell#35>", line 1, in <module>
    d
NameError: name 'd' is not defined
>>> d = dict.fromkeys("Fishc",250)
>>> d
{'F': 250, 'i': 250, 's': 250, 'h': 250, 'c': 250}
>>> d.clear()
>>> d
{}
>>> ["d.clear() ，将字典变为一个空字符"]
['d.clear() ，将字典变为一个空字符']
>>> 

d = dict({"one":1,"two":2},[("three",3),("four",4)])
Traceback (most recent call last):
  File "<pyshell#15>", line 1, in <module>
    d = dict({"one":1,"two":2},[("three",3),("four",4)])
TypeError: dict expected at most 1 argument, got 2
d = dict(one=1,{"two":2,"three":3})
SyntaxError: positional argument follows keyword argument
d = dict({"two":2,"three":3},one=1)
d
{'two': 2, 'three': 3, 'one': 1}