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。
