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)

Code

 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)

Result

(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

Code

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

Result

(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

Class Tuple