# l = [4,1,5,2,7] # l1 = reversed(l) # print(l1) # 保留原列表并返回一个反向的迭代器 # slice类似切片 # t = (123,32,1,34,56,122 ) # sli = slice(1,5,2) # print(t[sli]) # print(t[1:5:2]) # print(format('aaa', '<33')) # print(format('aaa', '>33')) # print(format('aaa', '^33')) # 转换为bytes类型 # print(bytes('你好',encoding='UTF-8')) # unicode转换成utf-8的bytes # print(bytearray('你好',encoding='UTF-8')) # 转换为bytearray类型，可修改里面 # 查unicode # print(ord('1')) # print(ord('好')) # print(chr(88)) # 查ascii # print(ascii('好')) # print(1) # print(all(['qwe','',True])) # all只要为空，就返回false # print(all(['qwe'])) # print(any(['qwe','',True])) # any有一个为空就返回true # 拉链，根据最短的那个输出元祖 # l = [1,2,3,4] # t = ('a','b',(1,2)) # d = {'name':'chen',1:1} # for i in zip(l,t,d): # print(i) # (1, 'a', 'name'),(2, 'b', 1) # def is_old(n): # return n % 2 == 1 # # filter(function or None, iterable) filter过滤,类似列表推导，只不过传入的是函数名和可迭代的 # 该函数根据function参数返回的结果是否为真来过滤list参数中的项,filter只管筛选，不会改变原来的值 # f = filter(is_old, [1,2,4,56,7,8,89]) # print(f) # for i in f: # print(i) # map两个参数一个是函数名，另一个是列表或元组,执行前后元素个数不变,值可能发生改变 # m = map(abs, [1,-4,6,-8]) # print(m) # for i in m: # print(i) # def map_cheng(x): # return x * x # # m = map(map_cheng, [1,2,3,4]) # for i in m: # print(i) # sorted生成新的列表而不改变原列表，占内存 l.sort()会改变 # l = [-2,5,4,1,-78] # sort_l = sorted(l) # print(sort_l) # sort_l2 = sorted(l, key=abs,reverse=True) # print(sort_l2)
# print(locals()) # print(globals()) # 迭代器 __next__() # next() # iter() # range(10) # print('__next__' in dir(range(1,11,2))) # dir 查看一个变量拥有的方法 # print(dir([])) # 查看帮助文档 # help(str) # f = open('w.py') # print(f.writable()) # id() # hash 对于相同可hash数据的hash值在一次程序的执行过程中总是不变的(不可变数据类型) # print(hash(12345)) # print(hash('sdfsdf')) # ret = input('input: ') # print('aaaaaaa',end='') #指定输出的结束符，默认end=' '回车 # print('aaaaaaa',sep='') #指定输出多个值之间的分隔符，这里输出一排a # print('aaaaaaa',file=f) #写入到f.write() # exec('print(123)') # 执行print,没有返回值 # eval('print(123)') # 有返回值 # print(bin(3)) # 二进制 # print(oct(10)) # 八进制 # print(hex(10)) # 十六进制 # print(abs(-34)) # 绝对值 # print(divmod(7,2)) # 求结果和求余，返回元祖(3,1) # print(round(3.1333, 3)) # 3.133 # print(pow(2,3)) # print(pow(2,3,3)) #pow幂运算，再对3求余 # print(sum([1,2,3,4])) # print(min([1,2,3,4])) # print(min((1,2,3,-4),key=abs)) # print(max([1,2,3,4])) # print(max((1,2,3,-4),key=abs))