1.三元表达式条件成立时的返回值 if 条件 else 条件不成立时的返回值三元表达式的意义就是让一些简单的if判断写成一行，减少代码量

def max2(x,y):    if x > y:        return x    else:        return yx=10y=20res = x if x > y else yprint(res)

2.列表生成式l=[item**2 for item in range(1,11)]print(l)print(next(iter(l)))  # 两次都是输出1print(next(iter(l)))  # 因为重新生成了一次对象res = l.__iter__()print(next(res))  1print(next(res))  4print(next(res))  9

names=['alex','wxx','lxx']

l=[]for name in names:    l.append(name + 'SB')names=l

names=[name+'SB' for name in names]print(names)

names=['alex','wxx','egon','lxx','zhangmingyan']l=[]for name in names:    if name != 'egon':        l.append(name + 'SB')names=lnames=[name+'SB' for name in names if name != 'egon']print(names)

列表推导式l=[item**2 for item in range(1,5) if item > 2]print(l)

names=['egon','alex_sb','wupeiqi','yuanhao']names=[name.upper() for name in names]print(names)names=['egon','alex_sb','wupeiqi','yuanhao']

nums=[len(name) for name in names if not name.endswith('sb')]print(nums)

字典生成式zip（） 拉链函数  两个可迭代对象之间一一匹配，如果有一个对象比较长，短的匹配完了就停止匹配。匹配后的结果以元组形式返回。字典通过items后得到的值和拉链函数对两个可迭代对象进行匹配得到的值都是元组形式。通过变量解压可以对元组解压。for k,v in dict.items() == for k,v in zip(s1,l)s1='hellopo'l1=[1,2,3,4,5,6,7]

res=zip(s1,l1) # <zip object at 0x0000019B07AFA8C8>  <<---res               # [('h', 1), ('e', 2), ('l', 3), ('l', 4), ('o', 5), ('p', 6), ('o', 7)]print(res)print(list(res))

keys=['name','age','sex']values=['egon',18,'male']

res=zip(keys,values)print(type(res))  # <class "zip">print(list(res))  # [('name', 'egon'), ('age', 18), ('sex', 'male')]print(list(res)) # [ ]d={}for item in zip(keys,values):    print(item)  # 通过变量解压操作  k,v = itemfor k,v in zip(keys,values):    d[k]=vprint(d){'name': 'egon', 'age': 18, 'sex': 'male'}

keys=['name','age','sex']values=['egon',18,'male']d={k:v for k,v in zip(keys,values)}print(d)

info={'name': 'egon', 'age': 18, 'sex': 'male'}

keys=info.keys()print(keys)iter_keys=keys.__iter__()values=info.values()print(values)

d={k:v for k,v in zip(keys,values)}print(d)

s={i for i in range(10)}print(s,type(s))  # set

生成器表达式g=(i for i in range(10))# print(g)

print(next(g))print(next(g))

nums=[11,22,33,44,55]print(max(nums))

with open(r'C:\Users\LENOVO\PycharmProjects\untitled2\a.txt',encoding='utf-8') as f:    nums=(len(line) for line in f)  # 生成器    print(next(nums))    print(next(nums))    print(next(nums))    # print(type(nums))    # print(max(nums))    # print(type(max))# 内置方法 max（nums）和for循环，list相似，max依次取值比较大小，返回较大的，再取值进行比较print(nums)  # nums在外部仍是存在的print(max(nums))  # 会抛出异常是因为文件已经关闭了，生成器无法取值print(max(nums))

nums是一个生成器，即使文件关闭，nums依然以生成器的形式存在。在文件中调用max方法,max方法会自动执行next操作

列表表达式l=['egg%s' %i for i in range(100)]print(l)

生成器g=('egg%s' %i for i in range(1000000000000))# print(g)print(next(g))print(next(g))