1、Python生成器表达式
1）、Python生成器表达式
语法格式：
(expr for iter_var in iterable)
(expr for iter_var in iterable ifcond_expr)
2）、自定义生成器
函数中使用yield，会返回一个生成器对象。yieldx
生成器使用示例：
In [1]:list((i**2 for i in range(1,11)))
Out[1]:[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
In [2]:def genNum(x):
...: y = 0
...: while y <= x:
...: yield y
...: y += 1
In [3]: g1= genNum(4)
In [4]:type(g1)
Out[4]:generator
In [5]:g1.next()
Out[5]:0
In [6]:g1.next()
Out[6]:1
In [7]:g1.next()
Out[7]:2
In [8]:g1.next()
Out[8]:3
In [9]:g1.next()
Out[9]:4
In [10]:g1.next()
--------------------------------------------------
StopIteration Traceback (most recent call last)
in()
----> 1g1.next()
StopIteration:
In [11]:def genNum(n):
....: i = 1
....: while i <= n:
....: yield i ** 2
....: i += 1
In [12]:g1 = genNum(20)
In [13]:for i in g1:
....: print i,
....:
1 4 9 1625 36 49 64 81 100 121 144 169 196 225 256 289 324 361400
2、Python装饰器
1）、装饰器本身是一个函数，用于装饰其它函数；
2）、功能：增强被装饰函数的功能；
装饰器一般接受一个函数对象作为参数，以对其进行增强
例1：装饰器使用示例
In [1]:def decorater(func):
...: def wrapper():
...: print "Just a Decorater!"
...: func()
...: raw_input('Please Input your name:')
...: return wrapper
...:
In [2]:@decorater
...:def show():
...: print "I am from China."
...:
In [3]:show()
Just aDecorater!
I am fromChina.
PleaseInput your name:Fieldyang
例2：对能够传入参数的函数进行装饰
In [1]:def decorater(func):
...: def wrapper(x):
...: print "Just a Decorater!"
...: func(x)
...: raw_input('Please Input your name:')
...: return wrapper
...:
In [2]:@decorater
...:def show(x):
...: print "I am from China.%s" %x
...:
In [3]:show('how are you ?')
Just aDecorater!
I am fromChina.how are you ?
PleaseInput your name:Fieldyang
3、Python递归
递归需要边界条件，递归前进段和递归返回段；
10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 *1
10 * （10-1）* （（10-1）-1）* ...
递归函数使用示例：
In [1]:def recursion(n):
...: if n <= 1: return 1
...: else: return n * recursion(n-1)
...:
#递归函数相当于如下过程：
In [2]: recursion(3) = 3 * recursion(2)= 3 * 2 *recursion(1)=3*2*1
KeyboardInterrupt
In [3]:recursion(3)
Out[3]:6
In [4]:recursion(4)
Out[4]:24
In [5]:recursion(5)
Out[5]:120
In [6]:recursion(10)
Out[6]:3628800
以上这篇对Python生成器、装饰器、递归的使用详解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。