python3_函数式编程

#!/usr/bin/python3
# -*- coding: utf-8 -*-

print("高阶函数(以函数作为参数)-------------")
def add(x,y,f):
    return f(x)+f(y)

print(add(5,-6,abs))

print("map/reduce-------------")
def normalize(name):
    return name.capitalize()

L1 = ['adam', 'LISA', 'barT']
print(list(map(normalize, L1)))

print("map/reduce-------------")
from functools import reduce
def multi(x,y):
    return x*y

def addone(x):
    return x+1
#map(f,[1,2,3]) 对列表每个成员执行操作f
#reduce(f,[1,2,3]) f(f(1,2),3) 依次计算
print(reduce(multi,map(addone,[1,2,3,1,1,1])))

print("filter-------------")
# filter(f,[1,2,3]) 对列表每一项进行f函数，如果结果为true则保留该值
# list(filter(f,[1,2,3])) 由于filter是惰性求值，需要list才能获得整个列表
def _odd_iter():
    n = 1
    while True:
        n = n + 2
        yield n
def _not_divisible(n):
    return lambda x: x % n > 0
#埃氏筛法
def primes():
    yield 2
    it = _odd_iter() # 初始序列
    while True:
        n = next(it) # 返回序列的第一个数
        yield n
        it = filter(_not_divisible(n), it) # 构造新序列
# 打印1000以内的素数:
for n in primes():
    if n < 2:
        print(n)
    else:
        break

print("sorted-------------")
#sorted 是python内置排序算法，可以额外接受一个函数
#内部比较两个元素时，按照分别给两个元素执行函数后的结果进行比较
sorted([36, 5, -12, 9, -21], key=abs)

print("闭包-------------")
#要记得_sum()中不应当引用会变化的变量
def sum(a,b):
    x=1
    def _sum():
        return (a+x)*(b+x)
    return _sum
f=sum(1,1)
print(f())

print("lambda-------------")
f=lambda x:x*x
print(f(2))
print(list(map(lambda x:x*x*x,[1,2,3])))

print("装饰器-------------")

def log(func):
    def wrapper(*args,**kw):
        print('call %s' % func.__name__)
        return func(*args,**kw)
    return wrapper

@log
def now():
    print('20191111')

now()

print("偏函数-------------")
print(int('100101001',base=2))
import functools
int2=functools.partial(int,base=2)
print(int2("10001"))
#模块的目录
import sys
print(sys.path)

print("private函数-------------")
def _hello():
    print("hello")
def hello():
    _hello()
hello()

'''
print("pillow库测试-------------")
from PIL import ImageFilter
from PIL import Image

imgF = Image.open("./test.jpg")
outF = imgF.filter(ImageFilter.DETAIL)
conF = imgF.filter(ImageFilter.CONTOUR)
edgeF = imgF.filter(ImageFilter.FIND_EDGES)
imgF.show()
outF.show()
conF.show()
edgeF.show()