python Memo

list&tuple 运算

乘以constant

>>> x = ((1,2),)
>>> x*2
((1, 2), (1, 2))
>>> x = ((1,2))
>>> x*2
(1, 2, 1, 2)
>>> 

从上面可以看出，tuple或者list和一个常数相乘，会复制元素得到一个新的tuple或list,需要注意的是有无逗号，这将决定是复制元素还是 "子tuple"。

tuple或list相加

>>> a = [1,2,3,4,5]
>>> a + [6]
[1, 2, 3, 4, 5, 6]
>>> a = (1,2,3,4,5)
>>> a +(6)

Traceback (most recent call last):
  File "<pyshell#189>", line 1, in <module>
    a +(6)
TypeError: can only concatenate tuple (not "int") to tuple
>>> a + (6,)
(1, 2, 3, 4, 5, 6)
>>> type((6))
<type ‘int‘>
>>> type([6])
<type ‘list‘>
>>> 

　　tuple和list在此处略有区别