【五】Python基础之数据结构:元组

元组:有序,一级元素不可以修改、不能被增加或删除(元组是可迭代对象),二级元素可以删除。

元组基本操作:索引、切片、循环、长度、包含

创建元组:

1 2 3

ages = (11, 22, 33, 44, 55) 或 ages = tuple((11, 22, 33, 44, 55))

一般写法括号内最后面加个英文逗号用来区分:

test = (,)

test1 = (11,22,)

例: test = (123, 456, 789, 'abc',)

元组运算符

与字符串一样,元组之间可以使用 + 号和 * 号进行运算。这就意味着他们可以组合和复制,运算后会生成一个新的元组。

Python 表达式

结果

描述

len((1, 2, 3))

3

计算元素个数

(1, 2, 3) + (4, 5, 6)

(1, 2, 3, 4, 5, 6)

连接

('Hi!',) * 4

('Hi!', 'Hi!', 'Hi!', 'Hi!')

复制

3 in (1, 2, 3)

True

元素是否存在

for x in (1, 2, 3): print (x,)

1 2 3

迭代


元组索引,截取

因为元组也是一个序列,所以我们可以访问元组中的指定位置的元素,也可以截取索引中的一段元素,如下所示:

元组:

L = ('Google', 'Taobao', 'Runoob')

Python 表达式

结果

描述

L[2]

'Runoob'

读取第三个元素

L[-2]

'Taobao'

反向读取;读取倒数第二个元素

L[1:]

('Taobao', 'Runoob')

截取元素,从第二个开始后的所有元素。

运行实例如下:

>>> L = ('Google', 'Taobao', 'Runoob')
>>> L[2]
'Runoob'
>>> L[-2]
'Taobao'
>>> L[1:]
('Taobao', 'Runoob')

元组内置函数

Python元组包含了以下内置函数

序号

方法及描述

实例

1

len(tuple) 计算元组元素个数。

>>> tuple1 = ('Google', 'Runoob', 'Taobao') >>> len(tuple1) 3 >>>

2

max(tuple) 返回元组中元素最大值。

>>> tuple2 = ('5', '4', '8') >>> max(tuple2) '8' >>>

3

min(tuple) 返回元组中元素最小值。

>>> tuple2 = ('5', '4', '8') >>> min(tuple2) '4' >>>

4

tuple(seq) 将列表转换为元组。

>>> list1= ['Google', 'Taobao', 'Runoob', 'Baidu'] >>> tuple1=tuple(list1) >>> tuple1 ('Google', 'Taobao', 'Runoob', 'Baidu')

1.通过索引取值

v  =  test[2]  #取出 789
print(v)

2.切片取值

1 2

v1, v2 = test[1:3]  #取出456和789 pritn(v1, v2)

  3.可以for循环,是可迭代对象

1 2

for item in test: print(item)

4.元组转化为字符串(元组内元素必须都是字符)

1 2 3

tu = ('abc', 'efg', 'hij',) tu1 = "".join(tu) print(tu1)

5.元组转化为列表

1 2

li = list(test) print(li)

6.增加元素问题

1 2 3 4

# tu[2]:元组 tu[3]:列表 tu[3][0]:元组 tu[6]:bool tu = ('nihao', 333, (44, 55,), [(888, 999,)], 54, 45, True) tu[3] = "aa"  # 报错,因为tu[3]作为tu元组的一级元组,不可修改,删除 tu[3].append('33') # tu[3]是tu元组的一级元素,只是不能对tu[3]本身进行修改、删除。但是可以对tu[3]进行list的方法

  7.tuple的count方法:获取指定元素在元组中出现的次数 

  count(self, value)

  参数:value:待查询出现次数的元素

1 2 3

tu = ('nihao', 333, (44, 55,), [(888, 999,)], 54, 333, True) v = tu.count(333) print(v)

8.tuple的index方法:获取指定元素的下标(就近原则,从左往右,找到第一个就结束)

  index(self, value, start=None, stop=None)

参数:value:待查询下标的元素

   start:查询起始下标

   stop:查询终止下标(查询到stop前一个下标)  

1 2 3

tu = ('nihao', 333, (44, 55,), [(888, 999,)], 54, 333, True) v = tu.index(333, 4, 7) print(v)

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 """
        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.
        """
        return 0

    def __add__(self, y): # real signature unknown; restored from __doc__
        """ x.__add__(y) <==> x+y """
        pass

    def __contains__(self, y): # real signature unknown; restored from __doc__
        """ x.__contains__(y) <==> y in x """
        pass

    def __eq__(self, y): # real signature unknown; restored from __doc__
        """ x.__eq__(y) <==> x==y """
        pass

    def __getattribute__(self, name): # real signature unknown; restored from __doc__
        """ x.__getattribute__('name') <==> x.name """
        pass

    def __getitem__(self, y): # real signature unknown; restored from __doc__
        """ x.__getitem__(y) <==> x[y] """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __getslice__(self, i, j): # real signature unknown; restored from __doc__
        """
        x.__getslice__(i, j) <==> x[i:j]
                   
                   Use of negative indices is not supported.
        """
        pass

    def __ge__(self, y): # real signature unknown; restored from __doc__
        """ x.__ge__(y) <==> x>=y """
        pass

    def __gt__(self, y): # real signature unknown; restored from __doc__
        """ x.__gt__(y) <==> x>y """
        pass

    def __hash__(self): # real signature unknown; restored from __doc__
        """ x.__hash__() <==> hash(x) """
        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): # real signature unknown; restored from __doc__
        """ x.__iter__() <==> iter(x) """
        pass

    def __len__(self): # real signature unknown; restored from __doc__
        """ x.__len__() <==> len(x) """
        pass

    def __le__(self, y): # real signature unknown; restored from __doc__
        """ x.__le__(y) <==> x<=y """
        pass

    def __lt__(self, y): # real signature unknown; restored from __doc__
        """ x.__lt__(y) <==> x<y """
        pass

    def __mul__(self, n): # real signature unknown; restored from __doc__
        """ x.__mul__(n) <==> x*n """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more): # real signature unknown; restored from __doc__
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __ne__(self, y): # real signature unknown; restored from __doc__
        """ x.__ne__(y) <==> x!=y """
        pass

    def __repr__(self): # real signature unknown; restored from __doc__
        """ x.__repr__() <==> repr(x) """
        pass

    def __rmul__(self, n): # real signature unknown; restored from __doc__
        """ x.__rmul__(n) <==> n*x """
        pass

    def __sizeof__(self): # real signature unknown; restored from __doc__
        """ T.__sizeof__() -- size of T in memory, in bytes """
        pass

tuple
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