lists
所有对象（数字、字符串、布尔等等）的有序集合序列。
>>> a = []
>>> a.append(1)
>>> a.append("abc")
>>> a.append(False)
>>> a
[1, 'abc', False]
dictionaries
字典 键值对
>>> dictionaries = {}
>>> dictionaries['first'] = 'a'
>>> dictionaries[1] = 2
>>> dictionaries
{'first': 'a', 1: 2}
sets
集合，可以从list生成,做交运算 &
>>> b = [1,2,3.4,5]
>>> setB = set(b)
>>> setB
{1, 2, 5, 3.4}
>> c = [1,2,6,7]
>>> setC = set(c)
>>> setC
{1, 2, 6, 7}
>>> setD = setB - setC
>>> setD
{5, 3.4}
缩进的作用
不需要括号，用缩进表示这是代码块。
>>> if 3 < 4 :
... print("hello world")
... print(1+1)
...
hello world
2
集合中的循环
>>> sA = set([8,7,6,5])
>>> for item in sA:
... print(item)
...
8
5
6
7
字典中的循环
>>> for item in dA:
... print(item, dA[item])
...
first a
1 2
第一个列表的2倍赋给另一个列表 列表表达式
>>> la = [1,1,2,3,5,8]
>>> lb = [item * 4 for item in la]
>>> lb
[4, 4, 8, 12, 20, 32]
>>> lc = []
>>> for item in la:
... lc.append(item * 4)
...
>>> lc
[4, 4, 8, 12, 20, 32]
>>> le = [item * 4 for item in la if item < 4]
>>> le
[4, 4, 8, 12]
