python笔记--廖雪峰站学习笔记(二)

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#生成一个从1到100的列表print(list(range(1,101)))#[1,2,3...,100]print([x * x for x in range(1,11) if x%2 ==0])#[4,16,36,64,100]print([x * x -1 for x in range(1,11) if x%3==1])#[0,15,48,99]print([x * x for x in range(1,11) if x%3==1])#[1,16,49,100]#二层循环，生成全排列print([m+n for n in 'abc' for m in 'xyz'])#使用os模块，遍历当前文件夹下的所有文件，只能说牛逼import osprint([d for d in os.listdir('.')])#在for循环中使用两个变量（类似foreach），遍历出字典dictdi = {'xiaoge':100,'xiaobai':90,'zz':80}for k,v in di.items():print(k,'=',v)#将数据字典dict转成列表listdi = {'xiaoge':'100','xiaobai':'90','zz':'80'}print([k + '=' + v for k, v in di.items()])#['xiaobai=90', 'xiaoge=100', 'zz=80']#将列表中的值转化成大小L = ['Xiaoge','Llll','Zhang','DAN']print([k.lower() for k in L])#遍历列表for k in L:print(k)#isinstance()函数判断变量的数据类型print(isinstance('xiaobai',int))#判断整型print(isinstance('xiaobai',str))#判断字符串#去掉数字和NoneL1 = ['Hello', 'World', 18, 'Apple', None]print([k for k in L1 if isinstance(k,str)])#得到下面结果：['Hello', 'World', 'Apple']

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