l = [1,2,3,4,5]

l.reverse()

print(l)

l = [1,2,3,4,5]

l2 = reversed(l)

print(l2)

l = (1,2,23,213,5612,342,43)

sli = slice(1,5,2)

print(l[sli])

print(l[1:5:2])

print(format('test', '<20'))

print(format('test', '>40'))

print(format('test', '^40'))

我拿到的是gbk编码的，我想转成utf-8编码

print(bytes('你好',encoding='GBK')) # unicode转换成GBK的bytes

print(bytes('你好',encoding='utf-8')) # unicode转换成utf-8的bytes

b_array = bytearray('你好',encoding='utf-8')

print(b_array)

print(b_array[0])

'\xe4\xbd\xa0\xe5\xa5\xbd'

s1 = 'alexa'

s2 = 'alexb'

print(ord('好'))

print(ord(''))

print(chr(97))

print(ascii('好'))

print(ascii(''))

name = 'egg'

print('你好%r'%name)

print(repr(''))

print(repr(1))

print(all(['a','',123]))

print(all(['a',123]))

print(all([0,123]))

print(any(['',True,0,[]]))

l = [1,2,3,4,5]

l2 = ['a','b','c','d']

l3 = ('*','**',[1,2])

d = {'k1':1,'k2':2}

for i in zip(l,l2,l3,d):

print(i)

def is_odd(x):

return x % 2 == 1

def is_str(s):

return s and str(s).strip()

ret = filter(is_odd, [1, 6, 7, 12, 17])

ret = filter(is_str, [1, 'hello','',' ',None,[], 6, 7, 'world', 12, 17])

print(ret)

for i in ret:

print(i)

[i for i in [1, 4, 6, 7, 9, 12, 17] if i % 2 == 1]

from math import sqrt

def func(num):

res = sqrt(num)

return res % 1 == 0

ret = filter(func,range(1,101))

for i in ret:

print(i)

ret = map(abs,[1,-4,6,-8])

print(ret)

for i in ret:

print(i)

filter 执行了filter之后的结果集合 <= 执行之前的个数

filter只管筛选，不会改变原来的值

map 执行前后元素个数不变，值可能发生改变

l = [1,-4,6,5,-10]

# l.sort(key = abs) # 在原列表的基础上进行排序

# print(l)

print(sorted(l,key=abs,reverse=True)) # 生成了一个新列表 不改变原列表 占内存

print(l)

l = [' ',[1,2],'hello world']

new_l = sorted(l,key=len)

print(new_l)

def add(x,y):

    return x+y

add = lambda x,y:x+y

    print(add(1,2))

dic={'k1':10,'k2':100,'k3':30}

def func(key):

    return dic[key]

print(max(dic,key=func)) #根据返回值判断最大值，返回值最大的那个参数是结果

print(max(dic,key=lambda key:dic[key]))

    max([1,2,3,4,5,-6,-7],key=abs)

ret = map(abs,[-1,2,-3,4])

for i in ret:

print(i)

def func(x):

return x**2

ret = map(func,[-1,2,-3,4])

for i in ret:

print(i)

ret = map(lambda x:x**2,[-1,2,-3,4])

def func(x):

return x>10

res = filter(func,[5,8,11,9,15])

for i in res:

print(i)

d = lambda p:p*2

t = lambda p:p*3

x = 2

x = d(x) #x = 4

x = t(x) #x = 12

x = d(x) #x = 24

print(x)

ret = zip((('a'),('b')),(('c'),('d')))

ret = map(lambda t:{t[0]:t[1]},ret)

print(list(ret))

# 方法一
t1=(('a'),('b'))
t2=(('c'),('d'))
# print(list(zip(t1,t2)))
print(list(map(lambda t:{t[0],t[1]},zip(t1,t2))))

# 方法二
print(list([{i,j} for i,j in zip(t1,t2)]))

#方法三
func = lambda t1,t2:[{i,j} for i,j in zip(t1,t2)]
ret = func(t1,t2)
print(ret)