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lst = [1,2,-3,1,2,-5] print([abs(i) for i in lst])
lst [1,2,-3,1,2,-5] print([i for i in enumerate(lst)]) print(i for i in enumerate(lst,10))
print(123,file = open('1.txt','w'))#输出到文件内
print(list('alex'))#结果是迭代出来的
print(dict(key = 1, a = 'alex'))#结果{'key':1,'a':'alex'} #面试:定义 print(dic(((1,2),(2,3),(3,4)))) print(dict([i for i in enumerate(range(20),1)]))
lst1 = [1,2,3,4,5] lst2 = ['a','b','c','d','f'] lst3 = ["alex",'ewr',"你好",""] lst4 = {'k1':1,'k2':2} print(list(zip(lst1,lst2))) print(dict(list(zip(lst1,lst2))))#面试 print(dict(zip(lst1,lst2))) print(list(zip(lst1,lst2,lst3))) print(list(zip(lst4,lst1)))
print(dir(list))
g = range(0,10) from collections import iterable,iterator print(isinstance(g,iterable))#判断是否是可迭代对象 print(isinstance(g,iterator))#判断是否是迭代器
重要的内置函数和匿名函数
lambda -->定义函数(一行函数),x,y 形参 x+y 返回值,只能返回一个数据类型。形参可以不写,返回值必须写
匿名函数的名字叫做lambda
f = lambda x, y:x+y print(f(1,2)) f = lambda x, y:(x,y) print(f(1,2)) print(f.__name__())#函数名就叫做lambda print(lambda x:x)#结果:内存地址 print((lambda x:x)(2))#调用函数 #面试1 print([lambda i:i*i for i in range(10)])#返回十次匿名函数的内存地址 lst = [lambda i:i*i for i in range(10)] print(lst[2](2)) #解构 lst = [] for i in range(10): def func(i): return i*i lst.append(func) print(lst[2](3))#结果 9 #2.不写形参 lst = [lambda :i*i for i in range(10)] print(lst[2]()) #解构 lst = [] for i in range(10): def func(): return i*i lst.append(func) print(lst[2]())#结果 81 # lst = (lambda i:i*i for i in range(5))#报错 print((lambda i:i*i for i in range(5)))#生成器的地址 #
print(format(13,">20"))#右对齐 print(format(13,"<20"))#左对齐 print(format(13,"^20"))#居中 print(format(13,"b"))#二进制 #进制,8位显示 print(format(13,"08b"))#二进制 print(format(13,"08d"))#十进制 print(format(13,"08o"))#八进制 print(format(13,"08x"))#十六进制
lst = [1,2,3,4,5,6] def func(s): return s>3 print(filter(func,lst))#返回对象内存地址 print(list(filter(func,lst)))#返回lst中>3的值 func就是定义的条件,lst是迭代对象 #用lambda print(list(filter(lambda x:x>3,lst)))
print(map(lambda x:x+1,[1,2,3,4,8,5]))#返回地址 print(list(map(lambda x:x+1,[1,2,3,5,4,6])))#
s1 = "alex" print(reversed(s1))#结果为内存地址 print(list(reversed(s1)))#结果:['x', 'e', 'l', 'a'] lst = [1,2,3,4,5] lst.reverse() print(s1) lst1 = list(reversed(lst)) print(lst) print(lst1) lst = [1,2,36,4,8] print(sorted(lst)) print(lst)#原数据不变 #降序 print(sorted(lst,reverse=treu)) #key dic = {'k1':1,'k2':3,'k3':56} print(sorted(dic,key=lambda x:dic[x],reverse=true)) #key指定查找最大值时的规则 print(max([1,2,-33,5],key=abs))
from functools import reduce print(reduce(lambda x,y:x+y,[1,2,3]))
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