Python列表生成式和生成器-优快云博客

本文详细介绍了Python中的生成式和生成器的概念与使用方法，包括生成式的语法糖及其实现方式，生成器的基本原理及其在实际编程中的应用，并通过具体示例展示了如何利用这些特性简化代码。

1、生成式

li = [x*x for x in xrange(1,10) if x%2 == 0]
print(li)

结果：

[4, 16, 36, 64]

def funa():

    a = []

    for x in xrange(1,10):

        if x%2 == 0:

            a.append(x*x)

    return a



print(funa())

结果：

[4, 16, 36, 64]

2、生成器

#列表生成器

#1. 最简单的方法，把原来的生成式的[]换成()就OK了

lt = (x * x for x in xrange(1,101) if x % 2 == 0)

print(lt)

print(type(lt))

print(lt.next())

print(lt.next())

print(lt.next())

print(lt.next())

结果：

生成器可以用for循环调用

# for i in lt:

#     print(i)

#2. 函数中定义列表生成器

def fib(n):

    sum = 0

    i = 0

    while(i<n):

        sum = sum + i

        i+=1

        # print(sum)

        yield (sum)

fib(10)

print(type(fib(10)))

结果：

# for i in fib(10):

#     print(i)

For循环结果：

3、用函数实现9*9乘法口诀

def sumsum(i):

    if i >=1:

        sumsum(i - 1)

        print(['%d * %d = %d' %(j, i, j*i) for j in xrange(1,i+1)])



sumsum(9)

结果：

['1 * 1 = 1']

['1 * 2 = 2', '2 * 2 = 4']

['1 * 3 = 3', '2 * 3 = 6', '3 * 3 = 9']

['1 * 4 = 4', '2 * 4 = 8', '3 * 4 = 12', '4 * 4 = 16']

['1 * 5 = 5', '2 * 5 = 10', '3 * 5 = 15', '4 * 5 = 20', '5 * 5 = 25']

['1 * 6 = 6', '2 * 6 = 12', '3 * 6 = 18', '4 * 6 = 24', '5 * 6 = 30', '6 * 6 = 36']

['1 * 7 = 7', '2 * 7 = 14', '3 * 7 = 21', '4 * 7 = 28', '5 * 7 = 35', '6 * 7 = 42', '7 * 7 = 49']

['1 * 8 = 8', '2 * 8 = 16', '3 * 8 = 24', '4 * 8 = 32', '5 * 8 = 40', '6 * 8 = 48', '7 * 8 = 56', '8 * 8 = 64']

['1 * 9 = 9', '2 * 9 = 18', '3 * 9 = 27', '4 * 9 = 36', '5 * 9 = 45', '6 * 9 = 54', '7 * 9 = 63', '8 * 9 = 72', '9 * 9 = 81']

转载于:https://my.oschina.net/peizh/blog/1560686