基础数据类型-tuple

Python中，元组tuple与list类似，不同之处在于tuple的元素不能修改，tuple使用()，list使用[]，

(1)元组的创建使用()，需要注意的是创建包含一个元素的元组：

tuple_number = ()
tuple_number = (1, ) #创建一个元素的元组，在元素后加逗号
print("type of (1) is:", type((1))) #(1)的类型是整形

type of (1) is: <class 'int'>

(2)元组的索引，切片，检查成员，加，乘

#索引
tuple_number = (1, 2, 3, 4, 5)
print("tuple_number[2]:", tuple_number[2])
#切片
print("tuple_number[1:4]:", tuple_number[1:4])#index = 4的元素不包含
#检查成员
if 6 in tuple_number:
    print("6 is in tuple_number")
else:
    print("6 is not in tuple_number")
#加
tuple_name = ('John', 'Paul')
print("tuple_number plus tuple_name:", tuple_number + tuple_name)
#乘
print("tuple_number * 2:", tuple_number * 2)

tuple_number[2]: 3
tuple_number[1:4]: (2, 3, 4)
6 is not in tuple_number
tuple_number plus tuple_name: (1, 2, 3, 4, 5, 'John', 'Paul')
tuple_number * 2: (1, 2, 3, 4, 5, 1, 2, 3, 4, 5)

(3)tuple的遍历和list一样： for number in tuple_number:print(number) 

(4)与list一样,tuple也有函数:len(),max(),min(),tuple()

(5)由于tuple的元素不允许修改，tuple的内置方法只有count(),index()

#方法
tuple_number = (1, 1, 2, 2, 2, 3, 3, 3, 3)
print("count of 2 in tuple_number:", tuple_number.count(2)) #元素出现的次数
print("index of first 3:", tuple_number.index(3)) #元素第一次出现的位置

count 2 in tuple_number: 3
index of first 3: 5

(6)最后看看tuple类的定义：

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