原地交换两个数a=10b=20a,b=b,aprint(b,a)print(a,b)output:10202010chaincomparisonn=10print(65]print(b)c=[(0,1),(2,3),(4,6)]d=[r[1]forrinc]print(d)输出：[6,8,7,9][1,3,6]列表??/元组切片a=[1,2,3,4,5,6]#(1,2,3,4,5,6)b=a[2:]c=a[1:2]#半闭半开print(b)print(c)输出：[3,4,5,6][2]一个元素在列表中出现的次数a=[1,2,3,3,2,4,5]print(a.count(2))output:2统计列表中的元素个数a=[1,2,3,3,2,4,5]#method1fromcollectionsimportCounterb=Counter(a)print(b)#method2c={i:a.count(i)foriinset(a)}print(c)输出：Counter({2:2,3:2,1:1,4:1,5:1}){1:1,2:2,3:2,4:1,5:1}列表d复制a=[1,2,3,3,2,4,5]b=list(set(a))print(a,b)输出：[1,2,3,3,2,4,5][1,2,3,4,5]字典推导a=[['name','Robin'],['age',30]]b={r[0]:r[1]forrina}print(b)输出：{'name':'Robin','age':30}字典生成a=[['name','Robin'],['age',30]]b=dict(a)print(b)输出：{'name':'Robin','age':30}字典到元组a={'name':'Robin','age':30}print(list(a.items()))output:[('name','Robin'),('age',30)]元素打包a=[1,2,3,4]b=['a','b','c','d']c=zip(a,b)print(list(c))输出：[(1,'a'),(2,'b'),(3,'c'),(4,'d')]字符串重复a='a'b=a*10print(b)输出：aaaaaaaaaa字符串拼接a=['Hello','World','!']b='~'.join(a)print(b)输出：Hello~World~!字符串包含a='HelloWorld!'print('World'ina)print('abc'ina)output:TrueFalse简化ifOperationa=1ifa==1ora==2ora==3ora==8:pass#notrecommendedifain[1,2,3,8,9]:pass#推荐输出：获取索引和元素#丑陋的代码a=['A','B','C']n=0foriina:print(n,i)n+=1foriinrange(len(a)):print(i,a[i])#recommendedcodeforn,iinenumerate(a):print(n,i)输出：0A1B2C0A1B2C0A1B2C函数参数deftest(a,b,*args,**kwargs):print(a,b,args,kwargs)test(1,2)test(1,2,3,4,t=5)n=[4,5]m={'x':6,'y':7}test(1,2,*n,**m)#结构转移，相当于test(1,2,3,4,x=6,y=7)输出：12(){}12(3,4){'t':5}12(4,5){'x':6、'y':7}地图函数a=[{'name':'A','id':1},{'name':'B','id':2}]b=map(lambdad:d['id'],a)print(list(b))#列表理解实现c=[d['id']fordina]print(c)output:[1,2][1,2]filterfunctiona=[1,4,5,6,2,8,3,7,9]b=filter(lambdai:i>5,a)print(list(b))#列表理解实现c=[iforiinaifi>5]print(c)输出：[6,8,7,9][6,8,7,9]max,min,sumfunctiona=[1,2,3,3,2,4,5]print(max(a))print(min(a))print(sum(a))output:5120简化了ifwithdictionary#丑陋的代码a=1ifa==1:b='A'elifa==2:b='B'else:b='C'print(b)#简化代码d={1:'A',2:'B'}b=d.get(a,'C')print(b)输出：AAA
