Tuple 可以理解为数组，初始化之后数组本身便不可更改。它是一种表示序列化数据的数据类型，目前只做初步学习，以后再做更深入的了解。
Tuples may be constructed in a number of ways:
1)Using a pair of parentheses to denote the empty tuple: ()
2)Using a trailing comma for a singleton tuple: a, or (a,)
3)Separating items with commas: a, b, c or (a, b, c)
4)Using the tuple() built-in: tuple() or tuple(iterable)
The constructor builds a tuple whose items are the same and in the same order as iterable‘s items. iterable may be either a sequence, a container that supports iteration, or an iterator object. If iterable is already a tuple, it is returned unchanged. For example, tuple('abc') returns ('a', 'b', 'c') and tuple( [1, 2, 3] ) returns (1, 2, 3). If no argument is given, the constructor creates a new empty tuple, ().
Note that it is actually the comma which makes a tuple, not the parentheses. The parentheses are optional, except in the empty tuple case, or when they are needed to avoid syntactic ambiguity. For example, f(a, b, c) is a function call with three arguments, while f((a, b, c)) is a function call with a 3-tuple as the sole argument.
因为tuple是一个序列类型，所以支持用下标来访问：
x = 1, 2, 3, 4, 5 x[0] # 1
可以一次性把元组里面的值，赋给多个变量：
stock = ('002582', 28.10, 28.80, 28.90, 28.00) code, open_price, close_price, high, low = stock # 依次赋值, code 为 '002582', open_price 为 28.10
也可以定义命名元组：
from collections import namedtuple
# this method would return a new type of Stock which is the subclass of tuple Stock = namedtuple('Stock', 'symbol price') stock = Stock ('0022582', 28.10) stock.symbol
今天的一些练习：
tuple_a = 1,3,5,7,9,11 tuple_b = 'hello', 'world' tuple_c = 'hello', tuple_d = tuple('hello') tuple_e = () tuple_f = (1,3,5,7,9,11,13,15) tuple_g = tuple('abc') tuple_h = tuple([1,3,5,7]) tuple_x, tuple_y, tuple_z = (2,4,(8,16)) print('tuple_a =',tuple_a) print('len(tuple_a) =',len(tuple_a)) print('tuple_a[1] =',tuple_a[1]) print('tuple_b =',tuple_b) print('tuple_c =',tuple_c) print('tuple_d =',tuple_d) print('tuple_e =',tuple_e) print('tuple_f =',tuple_f) print('tuple_g =',tuple_g) print('tuple_h =',tuple_h) print('tuple_x =',tuple_x) print('tuple_y =',tuple_y) print('tuple_z =',tuple_z) list_a = [1,3,5] tuple_i = tuple(list_a) print('list_a =',list_a) print('tuple_i =',tuple_i) list_a.append(7) print('list_a =',list_a) print('tuple_i =',tuple_i)
运行结果如下：
tuple_a = (1, 3, 5, 7, 9, 11)
len(tuple_a) = 6
tuple_a[1] = 3
tuple_b = ('hello', 'world')
tuple_c = ('hello',)
tuple_d = ('h', 'e', 'l', 'l', 'o')
tuple_e = ()
tuple_f = (1, 3, 5, 7, 9, 11, 13, 15)
tuple_g = ('a', 'b', 'c')
tuple_h = (1, 3, 5, 7)
tuple_x = 2
tuple_y = 4
tuple_z = (8, 16)
list_a = [1, 3, 5]
tuple_i = (1, 3, 5)
list_a = [1, 3, 5, 7]
tuple_i = (1, 3, 5)
