python课程第四周重点记录

names = iter(["alex","jack","rain"])   #声明列表的一个迭代器
names.__next__() #迭代

def cash_monkey(amount):
    while(amount>0):
        amount -= 100
        print("取钱啦")
        yield amount

atm = cash_monkey(500)
print("还剩%s"%atm.__next__())#__next__()方法相当于执行一次函数,停在yield语句处返回yield相当于return
print("还剩%s"%atm.__next__())
for i in cash_monkey(500): #for循环中自动调用__next__()方法
    print(i)
#在读取文件中使用
def read_file(fpath):
   BLOCK_SIZE =1024
   with open(fpath, ‘rb‘) as f:
       while True:
           block =f.read(BLOCK_SIZE)
           if block:
               yield block
           else:
               return

def h():
    print(‘Wen Chuan‘)
    m = yield 5 # 接收了send传过来的Fighting!
    print(m)
    d = yield 12
    print(‘We are together!‘)
c = h()
m = c.__next__() #m 获取了yield 5 的参数值 5
d = c.send(‘Fighting!‘) #d 获取了yield 12 的参数值12
print(‘We will never forget the date‘, m, ‘.‘, d)

‘‘‘
[0,1,2,3]
[0,1,2,3]
[0,1,2,3]
[0,1,2,3]
----------
[0,0,0,0]
[1,1,1,1]
[2,2,2,2]
[3,3,3,3]
‘‘‘
data = [[col for col in range(4)] for row in range(4)]
for i in range(len(data)):
    a = [data[i][i] for row in range(4)]
    print(a)

import re
match = re.match(r‘dog‘, ‘dog cat dog‘)   #匹配开始
match.group() #取得匹配上的元素
match = re.search(‘dog‘, ‘dog cat dog‘)  #匹配任意位置,只匹配一次
match.group()
match.start()  #匹配上的元素的开始位置
match.end()    #匹配上的元素的结束位置
match = re.findall(r‘dog‘, ‘dog cat dog‘) #所有匹配对象,得到的是一个列表
contactInfo = ‘Doe, John: 555-1212‘
match = re.search(r‘(\w+), (\w+): (\S+)‘, contactInfo) #分成3个子串
match.group(1) #Doe
match.group(2) #John
match.group(3) #555-1212
match.group(0) #匹配所有Doe, John: 555-1212