Python全栈之路Day22

def func():
    n=0
    while True:
        yield n
        n += 1
g=func()
res=next(g)
for i in g:
    pass

def eater(name):
    print(‘%s start to eat ‘%name)
    while True：
        food=yield
        print(‘%s eat %s‘%(name,food))
e=eater(‘zhejiangF4‘)

def foo(func):
    def foo1(*args,**kwargs):
        res = func(*args,**kwargs)
        next(res)
        return res        #此处理解 生成器是一次性的
    return foo1

@foo        #eater = foo(eater) = foo1
def eater(name):
    print(‘%s start to eat food ‘% name)
    food_list = []
    while True:
        food = yield food_list
        print(‘%s get %s, to start eat ‘% (name, food))
        food_list.append(food)
    print(‘Done‘)

e = eater(‘钢蛋‘)        #foo1(‘钢蛋‘)
print(e.send(‘123‘))

from urllib.request import urlopen

def my_next(func):
    def foo(*args,**kwargs):
        res = func(*args,**kwargs)
        next(res)
        return res
    return foo

@my_next
def get():
    while True:
        url = yield
        res = urlopen(url).read()        #爬网页返回值
        print(res)        #输出爬网页结果

g=get()
g.send(‘http://www.baidu.com‘)
g.send(‘http://www.python.org‘)

# grep -rl ‘python‘ C:\egon
import os

#装饰器，将生成器next初始化
def init(func):
    def foo(*args,**kwargs):
        res = func(*args,**kwargs)
        next(res)
        return res
    return foo

@init
def search(target):
    ‘查找文件绝对路径‘
    while True:
        dir_path = yield        #此yield放在while外还是内有疑问:yield放在while外就会造成死循环，无法进行下次yield
        g = os.walk(dir_path)        #g为迭代器
        for i in g:
            # print(i)
            for j in i[-1]:
                file_path = ‘%s\\%s‘%(i[0],j)
                target.send(file_path)

@init
def opener(target):
    ‘打开文件获取文件句柄‘
    while True:
        file_path = yield
        with open(file_path) as f:
            target.send((f,file_path))        #send传递两个文件时，需加括号

@init
def cat(target):
    ‘读取文件内容‘
    while True:
        f,file_path = yield
        for line in f:        #读取一行文件
            target.send((line,file_path))

@init
def grep(target,pattern):    #传递两个参数，其中pattern为要过滤的字符串
    ‘过滤文件一行中是否有python‘
    while True:
        line,file_path = yield
        if pattern in line:
            target.send(file_path)        #需传递文件路径

@init
def printer():
    ‘打印文件路径‘
    while True:
        file_path = yield
        print(file_path)

g=search(opener(cat(grep(printer(),‘python‘))))
g.send(‘C:\\egon‘)

egg_list = []

for i in range(100):
    egg_list.append(‘egg%s‘% i)
print(egg_list)

egg_list = [‘egg%s‘%i for i in range(100)]
print(egg_list)

#列表内只会添加大于50的数字
egg_list = [‘egg%s‘%i for i in range(100) if i >50]
print(egg_list)

[expression for item1 in interable if condition1
                    for item2 in interable if condition2
                    …
                    for itemN in interable if conditionN
                    ]

res = []
for item1 in interable:
    if condition1:
        for item2 in interable:
            if condition2:
                …
                for itemN in interable:
                    if conditionN:
                        res.append(expression )

import os

g = os.walk(‘C:\\egon‘)
l = [‘%s\\%s‘% (i[0],j) for i in g for j in i[-1]]
print(l)
#[‘C:\\egon\\a.txt - 副本.txt‘, ‘C:\\egon\\a.txt.txt‘, ‘C:\\egon\\a\\a.txt.txt‘, ‘C:\\egon\\a\\a2.txt.txt‘, ‘C:\\egon\\b\\a.txt.txt‘, ‘C:\\egon\\b\\a1.txt.txt‘]

name = ‘alex‘
name = ‘egon‘

res = ‘sb‘ if name ==‘alex‘ else ‘shuai‘
print(res)        #输出shuai

(expression for item1 in interable if condition1
                    for item2 in interable if condition2
                    …
                    for itemN in interable if conditionN
                    )

#读取文件，并去掉每一行两头空格
f = open(‘a.txt‘)
g= (line.strip() for line in f)
print(next(g))

#鸡蛋  5  3
#特斯拉 10000000.2  5
#上衣  1000    3
#裤子  2000    3
#袜子  100
#读取包含以上信息的文件，并计算总共花费

#第一种传统写法
total = []
with open(‘b.txt‘,‘r‘,encoding=‘utf-8‘) as f:
    for line in f:
        goods=line.split()    #split用法及返回值需加强
        # print(goods)
        res = float(goods[1])*float(goods[-1])
        total.append(res)
print(total)
print(sum(total))

#第二种声明式编程写法
f=open(‘b.txt‘,‘r‘,encoding=‘utf-8‘)    #不能用with 否则会IO操作报错
total=(float(line.split()[1])*float(line.split()[-1]) for line in f)

print(total)
print(sum(total))

#[{‘name‘: ‘袜子‘, ‘price‘: ‘100‘, ‘num‘: ‘3‘}, {‘name‘: ‘袜子‘, ‘price‘: ‘100‘, ‘num‘: ‘3‘}, {‘name‘: ‘袜子‘, ‘price‘: ‘100‘, ‘num‘: ‘3‘}, {‘name‘: ‘袜子‘, ‘price‘: ‘100‘, ‘num‘: ‘3‘}, {‘name‘: ‘袜子‘, ‘price‘: ‘100‘, ‘num‘: ‘3‘}]
# 基本写法
res = []
d = {}

with open(‘b.txt‘,‘r‘,encoding=‘utf-8‘) as f:
    for line in f:
        l = line.split()
        d[‘name‘] = l[0]
        d[‘price‘] = l[1]
        d[‘num‘] = l[2]
        res.append(d)
print(res)

with open(‘b.txt‘,‘r‘,encoding=‘utf-8‘) as f:
    res = (line.split() for line in f)
    dic_g = ({‘name‘:line[0],‘price‘:line[1],‘num‘:line[2]} for line in res)
    goods_dic = next(dic_g)
    print(goods_dic[‘num‘])

with open(‘b.txt‘) as f:
    d = f
print(d)        #有内存地址，不是很理解
print(next(d))    #报错