列表推导式

列表推导式：轻量级循环创建列表

1、基本方式

a = [x for x in range(4)]	
	# a = [0, 1, 2, 3]
a = [x for x in range(3, 4)]	
	# a = [3,]
a = [x for x in range(3, 15, 2)]
	# a = [3, 5, 7, 9, 11, 13]

2、在循环中使用if

a = [x for x in range(3, 10) if x%2 == 0]
	# a = [4, 6, 8]
a = [x for x in range(3, 10) if x%2 != 0]
	# a = [3, 5, 7, 9]

3、多个for循环

a = [(x, y) for x in range(1, 3) for y in range(3)]
	# a = [(1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]
a = [(x, y, z) for x in range(1, 3) for y in range(3) for z in range(4, 6)]

4、其它

a = [x for x in range(1,101)]
b = [a[x:x+3] for x in range(0,len(a),3)]
	# b = [[1, 2, 3], [4, 5, 6], ..., [97, 98, 99], [100]]

5、嵌套列表

a = [[1,2,3],[4,5],[6],[7,8,9]]
b = [y for x in a for y in x]
	# b = [1, 2, 3, 4, 5, 6, 7, 8, 9]