Python基本数据类型(元组)

Posted 2022-01-16 lzc69

基本数据类型

四、元组

元组(Tuple)是一种与列表类似的序列类型。元组的基本用法与列表十分类似。只不过元组一旦创建，就不能改变，因此，元组可以看成是一种不可变的列表。

1.元组格式

Python用一对括号“（）”生成元组，中间的元素用逗号“，”隔开。尽量在最后元素后面加上一个额外的逗号“，”加以区分括号与元组，特别是只含单元素的元组：

 

tu = (11,22,"alex",[(33,44)],)

 

2.元组与列表的相互转换

列表和元组可以使用tuple()函数和list()函数相互转换：

li = [3,6,1,5,4,6]
print(tuple(li))        #结果为：(3, 6, 1, 5, 4, 6)
tu = (11,22,"alex",[(33,44)],)
print(list(tu))        #结果为：[11, 22, ‘alex‘, [(33, 44)]]

3.索引和切片

对于元组来说，只能通过索引和切片来取值，不能进行修改操作。

tu = (11,22,"alex",[(33,44)],)
print(tu[3][0][1])      #结果为：44
print(tu[1:-1])       #结果为：(22, ‘alex‘)

4.元组的方法

由于元组是不可变的，所有它只支持.count()方法和.index()方法，用法与列表一致：

.count()方法是计算元组的指定元素出现的次数。

tu = (11,22,"alex",[(33,44)],22,)
print(tu.count(22))     #结果为：2

.index()方法是获取指定元素第一次出现的索引位置。

tu = (11,22,"alex",[(33,44)],22,)
print(tu.index(22))      #结果为：1

元组所有方法归纳：

  1 lass tuple(object):
  2     """
  3     tuple() -> empty tuple
  4     tuple(iterable) -> tuple initialized from iterable‘s items
  5     
  6     If the argument is a tuple, the return value is the same object.
  7     """
  8     def count(self, value): # real signature unknown; restored from __doc__
  9         """ T.count(value) -> integer -- return number of occurrences of value """
 10         return 0
 11 
 12     def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
 13         """
 14         T.index(value, [start, [stop]]) -> integer -- return first index of value.
 15         Raises ValueError if the value is not present.
 16         """
 17         return 0
 18 
 19     def __add__(self, y): # real signature unknown; restored from __doc__
 20         """ x.__add__(y) <==> x+y """
 21         pass
 22 
 23     def __contains__(self, y): # real signature unknown; restored from __doc__
 24         """ x.__contains__(y) <==> y in x """
 25         pass
 26 
 27     def __eq__(self, y): # real signature unknown; restored from __doc__
 28         """ x.__eq__(y) <==> x==y """
 29         pass
 30 
 31     def __getattribute__(self, name): # real signature unknown; restored from __doc__
 32         """ x.__getattribute__(‘name‘) <==> x.name """
 33         pass
 34 
 35     def __getitem__(self, y): # real signature unknown; restored from __doc__
 36         """ x.__getitem__(y) <==> x[y] """
 37         pass
 38 
 39     def __getnewargs__(self, *args, **kwargs): # real signature unknown
 40         pass
 41 
 42     def __getslice__(self, i, j): # real signature unknown; restored from __doc__
 43         """
 44         x.__getslice__(i, j) <==> x[i:j]
 45                    
 46                    Use of negative indices is not supported.
 47         """
 48         pass
 49 
 50     def __ge__(self, y): # real signature unknown; restored from __doc__
 51         """ x.__ge__(y) <==> x>=y """
 52         pass
 53 
 54     def __gt__(self, y): # real signature unknown; restored from __doc__
 55         """ x.__gt__(y) <==> x>y """
 56         pass
 57 
 58     def __hash__(self): # real signature unknown; restored from __doc__
 59         """ x.__hash__() <==> hash(x) """
 60         pass
 61 
 62     def __init__(self, seq=()): # known special case of tuple.__init__
 63         """
 64         tuple() -> empty tuple
 65         tuple(iterable) -> tuple initialized from iterable‘s items
 66         
 67         If the argument is a tuple, the return value is the same object.
 68         # (copied from class doc)
 69         """
 70         pass
 71 
 72     def __iter__(self): # real signature unknown; restored from __doc__
 73         """ x.__iter__() <==> iter(x) """
 74         pass
 75 
 76     def __len__(self): # real signature unknown; restored from __doc__
 77         """ x.__len__() <==> len(x) """
 78         pass
 79 
 80     def __le__(self, y): # real signature unknown; restored from __doc__
 81         """ x.__le__(y) <==> x<=y """
 82         pass
 83 
 84     def __lt__(self, y): # real signature unknown; restored from __doc__
 85         """ x.__lt__(y) <==> x<y """
 86         pass
 87 
 88     def __mul__(self, n): # real signature unknown; restored from __doc__
 89         """ x.__mul__(n) <==> x*n """
 90         pass
 91 
 92     @staticmethod # known case of __new__
 93     def __new__(S, *more): # real signature unknown; restored from __doc__
 94         """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
 95         pass
 96 
 97     def __ne__(self, y): # real signature unknown; restored from __doc__
 98         """ x.__ne__(y) <==> x!=y """
 99         pass
100 
101     def __repr__(self): # real signature unknown; restored from __doc__
102         """ x.__repr__() <==> repr(x) """
103         pass
104 
105     def __rmul__(self, n): # real signature unknown; restored from __doc__
106         """ x.__rmul__(n) <==> n*x """
107         pass
108 
109     def __sizeof__(self): # real signature unknown; restored from __doc__
110         """ T.__sizeof__() -- size of T in memory, in bytes """
111         pass
112 
113 tuple

tuple