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Python數(shù)據(jù)類型詳解（三）元祖：tuple

更新時(shí)間：2016年05月08日 09:40:23 投稿：hebedich

本文給大家介紹的是Python數(shù)據(jù)類型中的元祖（tuple）,簡單的說Tuple,與列表一樣，元素也是不可變的，但與列表不同，在一個(gè)元祖可以包含不同類型的元素

一.基本數(shù)據(jù)類型

　　整數(shù)：int
　　字符串：str(注：\t等于一個(gè)tab鍵)
　　布爾值： bool
　　列表：list
　　列表用[]
　　元祖：tuple
　　元祖用（）
　　字典：dict
注：所有的數(shù)據(jù)類型都存在想對(duì)應(yīng)的類列里，元祖和列表功能一樣，列表可以修改，元祖不能修改。

二.列表所有數(shù)據(jù)類型：

基本操作：

索引，切片，長度，包含，循環(huán)

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(價(jià)值)- >整數(shù),返回值的出現(xiàn)次數(shù)）
    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。指數(shù)(價(jià)值,[開始,[不要]])- >整數(shù),返回第一索引值。提出了ValueError如果不存在的價(jià)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.所有元祖數(shù)據(jù)類型舉例

#count 用于計(jì)算元素出現(xiàn)的個(gè)數(shù)
name_tuple = ("zhangyanlin","suoning","nick")
print(name_tuple.count('zhangyanlin'))
 
#index獲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減1的元素
name_tuple = ("zhangyanlin","suoning","nick")
print(name_tuple[0:len(name_tuple)-1])

六.總長度len

#取出最后一位減1的元素
name_tuple = ("zhangyanlin","suoning","nick")
print(name_tuple[len(name_tuple)-1])

七.for循環(huán)

name_tuple = ("zhangyanlin","suoning","nick")
for i in name_tuple:
  print(i)

那么使用 tuple 有什么好處呢？

Tuple 比 list 操作速度快。如果您定義了一個(gè)值的常量集，并且唯一要用它做的是不斷地遍歷它，請(qǐng)使用 tuple 代替 list。
如果對(duì)不需要修改的數(shù)據(jù)進(jìn)行 “寫保護(hù)”，可以使代碼更安全。使用 tuple 而不是 list 如同擁有一個(gè)隱含的 assert 語句，說明這一數(shù)據(jù)是常量。如果必須要改變這些值，則需要執(zhí)行 tuple 到 list 的轉(zhuǎn)換 (需要使用一個(gè)特殊的函數(shù))。

還記得我說過 dictionary keys 可以是字符串，整數(shù)和 “其它幾種類型”嗎？Tuples 就是這些類型之一。Tuples 可以在 dictionary 中被用做 key，但是 list 不行。實(shí)際上，事情要比這更復(fù)雜。Dictionary key 必須是不可變的。Tuple 本身是不可改變的，但是如果您有一個(gè) list 的 tuple，那就認(rèn)為是可變的了，用做 dictionary key 就是不安全的。只有字符串、整數(shù)或其它對(duì) dictionary 安全的 tuple 才可以用作 dictionary key。

Tuples 可以用在字符串格式化中，我們會(huì)很快看到。

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