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。