Python高级特性-生成器

前言

生成器相比普通迭代器的实现，不会像普通迭代器生成完整集合返回，而是一边循环一边计算的机制，从而节省大量的空间。

普通迭代器

def triangles(line):
    result = []
    for x in range(line):
        array = []
        value = 1
        for x1 in range(x + 1):
            if x > 1 and 0 < x1 < x:
                value = value + result[x - 1][x1]
                array.append(value)
                value = result[x - 1][x1]
            else:
                array.append(1)
        result.append(array)
    return result

生成器

def triangles(line):
    last_array = None
    for x in range(line):
        array = []
        value = 1
        for x1 in range(x + 1):
            if x > 1 and 0 < x1 < x:
                value = value + last_array[x1]
                array.append(value)
                value = last_array[x1]
            else:
                array.append(1)
        last_array = array
        yield array


def triangles():
    array = [1]
    yield array
    while True:
        array = [v + w for v, w in zip([0] + array, array + [0])]
        yield array

测试

两种实现方式，结果都是一样的

[1]
[1, 1]
[1, 2, 1]
[1, 3, 3, 1]
[1, 4, 6, 4, 1]
[1, 5, 10, 10, 5, 1]
[1, 6, 15, 20, 15, 6, 1]
[1, 7, 21, 35, 35, 21, 7, 1]
[1, 8, 28, 56, 70, 56, 28, 8, 1]
[1, 9, 36, 84, 126, 126, 84, 36, 9, 1]

Process finished with exit code 0