Python数据类型详解(三)元祖:tuple
一.基本数据类型
整数:int
字符串:str(注:\t等于一个tab键)
布尔值: bool
列表:list
列表用[]
元祖:tuple
元祖用()
字典:dict
注:所有的数据类型都存在想对应的类列里,元祖和列表功能一样,列表可以修改,元祖不能修改。
二.列表所有数据类型:
基本操作:
索引,切片,长度,包含,循环
class tuple(object): """ tuple() -> empty tuple tuple(iterable) -> tuple initialized from iterable's items If the argument is a tuple, the return value is the same object. """ def count(self, value): # real signature unknown; restored from __doc__ """ T.count(value) -> integer -- return number of occurrences of value """ (T.count(价值)- >整数,返回值的出现次数) return 0 def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ """ T.index(value, [start, [stop]]) -> integer -- return first index of value. Raises ValueError if the value is not present. """ (T。指数(价值,[开始,[不要]])- >整数,返回第一索引值。提出了ValueError如果不存在的价值。) return 0 def __add__(self, *args, **kwargs): # real signature unknown """ Return self+value. """ pass def __contains__(self, *args, **kwargs): # real signature unknown """ Return key in self. """ 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, *args, **kwargs): # real signature unknown """ Return self[key]. """ pass def __getnewargs__(self, *args, **kwargs): # real signature unknown 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 __hash__(self, *args, **kwargs): # real signature unknown """ Return hash(self). """ pass def __init__(self, seq=()): # known special case of tuple.__init__ """ tuple() -> empty tuple tuple(iterable) -> tuple initialized from iterable's items If the argument is a tuple, the return value is the same object. # (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 def __mul__(self, *args, **kwargs): # real signature unknown """ Return self*value.n """ 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 __rmul__(self, *args, **kwargs): # real signature unknown """ Return self*value. """ pass
三.所有元祖数据类型举例
#count 用于计算元素出现的个数 name_tuple = ("zhangyanlin","suoning","nick") print(name_tuple.count('zhangyanlin')) #index获取指定元素的指定位置 name_tuple = ("zhangyanlin","suoning","nick") print(name_tuple.index('zhangyanlin'))
四.索引
name_tuple = ("zhangyanlin","suoning","nick") print(name_tuple[1])
五.切片
#取出第一位到最后一位减1的元素 name_tuple = ("zhangyanlin","suoning","nick") print(name_tuple[0:len(name_tuple)-1])
六.总长度len
#取出最后一位减1的元素 name_tuple = ("zhangyanlin","suoning","nick") print(name_tuple[len(name_tuple)-1])
七.for循环
name_tuple = ("zhangyanlin","suoning","nick") for i in name_tuple: print(i)
那么使用 tuple 有什么好处呢?
Tuple 比 list 操作速度快。如果您定义了一个值的常量集,并且唯一要用它做的是不断地遍历它,请使用 tuple 代替 list。
如果对不需要修改的数据进行 “写保护”,可以使代码更安全。使用 tuple 而不是 list 如同拥有一个隐含的 assert 语句,说明这一数据是常量。如果必须要改变这些值,则需要执行 tuple 到 list 的转换 (需要使用一个特殊的函数)。
还记得我说过 dictionary keys 可以是字符串,整数和 “其它几种类型”吗?Tuples 就是这些类型之一。Tuples 可以在 dictionary 中被用做 key,但是 list 不行。实际上,事情要比这更复杂。Dictionary key 必须是不可变的。Tuple 本身是不可改变的,但是如果您有一个 list 的 tuple,那就认为是可变的了,用做 dictionary key 就是不安全的。只有字符串、整数或其它对 dictionary 安全的 tuple 才可以用作 dictionary key。
Tuples 可以用在字符串格式化中,我们会很快看到。

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