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发表于 2021-12-8 19:46:05
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显示全部楼层
- >>> ["改"]
- ['改']
- >>> d = dict.fromkeys("FishC")
- >>> d
- {'F': None, 'i': None, 's': None, 'h': None, 'C': None}
- >>> d["s"] = 115
- >>> d
- {'F': None, 'i': None, 's': 115, 'h': None, 'C': None}
- >>> ["update([other]) 可以支持同时给它传入多个键值对，也可以直接给他传入另外一个字典，或者一个包含键值对的可迭代对象"]
- ['update([other]) 可以支持同时给它传入多个键值对，也可以直接给他传入另外一个字典，或者一个包含键值对的可迭代对象']
- >>> d.update({"i":105,"h":104})
- >>> d
- {'F': None, 'i': 105, 's': 115, 'h': 104, 'C': None}
- >>> d.update("F" = 70,"C "= 67)
- SyntaxError: expression cannot contain assignment, perhaps you meant "=="?
- >>> d.update(F ='70',C = '67')
- >>> d
- {'F': '70', 'i': 105, 's': 115, 'h': 104, 'C': '67'}
- >>> d['C']
- '67'
- >>> d["c"]
- Traceback (most recent call last):
- File "<pyshell#12>", line 1, in <module>
- d["c"]
- KeyError: 'c'
- >>> ["get(key[,default]) 方法，它可以存入一个default 参数，指定当找不到键的时候返回的值"]
- ['get(key[,default]) 方法，它可以存入一个default 参数，指定当找不到键的时候返回的值']
- >>> d.get('c',"这里没有c")
- '这里没有c'
- >>> ["setdefault(key[,default]),当我们需要查找一个键是否存在于字典中，如果在，则返回它对应的值，如果不在，则给它指定一个新的值"]
- ['setdefault(key[,default]),当我们需要查找一个键是否存在于字典中，如果在，则返回它对应的值，如果不在，则给它指定一个新的值']
- >>> d.setdefault('c','code')
- 'code'
- >>> d.setdefault('C','code')
- '67'
- >>> ['items() keys() values() 这三个分别用于获取字典的键值对、键和值三者的视图对象 视图对象即字典的动态视图，这就意味着当字典的内容发生改变的时候，视图对象的内容也会相应地跟着改变。']
- ['items() keys() values() 这三个分别用于获取字典的键值对、键和值三者的视图对象 视图对象即字典的动态视图，这就意味着当字典的内容发生改变的时候，视图对象的内容也会相应地跟着改变。']
- >>> d
- {'F': '70', 'i': 105, 's': 115, 'h': 104, 'C': '67', 'c': 'code'}
- >>> keys = d.keys()
- >>> values = d.values()
- >>> items = d.items()
- >>> items
- dict_items([('F', '70'), ('i', 105), ('s', 115), ('h', 104), ('C', '67'), ('c', 'code')])
- >>> keys
- dict_keys(['F', 'i', 's', 'h', 'C', 'c'])
- >>> valuse
- Traceback (most recent call last):
- File "<pyshell#25>", line 1, in <module>
- valuse
- NameError: name 'valuse' is not defined
- >>> values
- dict_values(['70', 105, 115, 104, '67', 'code'])
- >>> d.pop('c')
- 'code'
- >>> items
- dict_items([('F', '70'), ('i', 105), ('s', 115), ('h', 104), ('C', '67')])
- >>> keys
- dict_keys(['F', 'i', 's', 'h', 'C'])
- >>> values
- dict_values(['70', 105, 115, 104, '67'])
- >>> e = d.copy()
- >>> e
- {'F': '70', 'i': 105, 's': 115, 'h': 104, 'C': '67'}
- >>> ['copy() 也可以用于字典的浅拷贝']
- ['copy() 也可以用于字典的浅拷贝']
- >>> len(d)
- 5
- >>> 'C' in d
- True
- >>> 'c' not in d
- True
- >>> list(d)
- ['F', 'i', 's', 'h', 'C']
- >>> lisy(d.values)
- Traceback (most recent call last):
- File "<pyshell#38>", line 1, in <module>
- lisy(d.values)
- NameError: name 'lisy' is not defined
- >>> list(d.values)
- Traceback (most recent call last):
- File "<pyshell#39>", line 1, in <module>
- list(d.values)
- TypeError: 'builtin_function_or_method' object is not iterable
- >>> list(d.values)
- Traceback (most recent call last):
- File "<pyshell#40>", line 1, in <module>
- list(d.values)
- TypeError: 'builtin_function_or_method' object is not iterable
- >>> list(d.values())
- ['70', 105, 115, 104, '67']
- >>> e = iter(d)
- >>> next(e)
- 'F'
- >>> next(e)
- 'i'
- >>> next(e)
- 's'
- >>> next(e)
- 'h'
- >>> next(e)
- 'C'
- >>> next(e)
- Traceback (most recent call last):
- File "<pyshell#48>", line 1, in <module>
- next(e)
- StopIteration
- >>> list(reversed(d.values()))
- ['67', 104, 115, 105, '70']
- >>> ['嵌套']
- ['嵌套']
- >>> d = {'吕布':{'语文':60,'数学':70,'英语':80},'小关关':{'语文':80,'数学':90,'英语':70}}
- >>> d
- {'吕布': {'语文': 60, '数学': 70, '英语': 80}, '小关关': {'语文': 80, '数学': 90, '英语': 70}}
- >>> d['吕布']['数学']
- 70
- >>> d = {'吕布':[60,70,80],'小关关':[80.90,70]}
- >>> d['吕布'][1]
- 70
- >>> ['上述即为字典嵌套序列']
- ['上述即为字典嵌套序列']
- >>> d = {'F':70,'i':105,'s':115,'h':104,'C':67}
- >>> b = {v:k for k,v in d.items()}
- >>> b
- {70: 'F', 105: 'i', 115: 's', 104: 'h', 67: 'C'}
- >>> c = {v:k for k,v in d.items() if v > 100}
- >>> c
- {105: 'i', 115: 's', 104: 'h'}
- >>> d = {x:ord(x) for x in "FishC"}
- >>> d
- {'F': 70, 'i': 105, 's': 115, 'h': 104, 'C': 67}
- >>> ['ord() 函数用于返回 字符的 unicode 编码']
- ['ord() 函数用于返回 字符的 unicode 编码']
- >>> d = {x:y for x in [1,3,5] for y in [2,4,6]}
- >>> d
- {1: 6, 3: 6, 5: 6}
- >>> ['上述 依次返回‘1:2,1:4’，但是 1:4 会将 1:2 替换，因此最后返回 1:6,同理返回 3:6, 5:6, 这即是字典的不可重复性']
- ['上述 依次返回‘1:2,1:4’，但是 1:4 会将 1:2 替换，因此最后返回 1:6,同理返回 3:6, 5:6, 这即是字典的不可重复性']
- >>>
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