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  • 8.30

    列表内置方法

    只给列表用

    lt = [1,2,3]
    

    1.索引取值/索引修改值

    print(lt[2]) #3取
    lt[0] = 2
    print(lt) #[2,2,3]改
    

    2.索引切片

    print(lt[0:1])
    

    3.成员运算in/not in

    print(2 in lt) #T
    print(2 not in lt) #F
    

    4.for循环

    for i in lt:
    	print(i)
    

    5.长度len

    print(len(lt)) #3
    

    6.append():追加值

    lt.append(4) #[2,2,3,4]
    

    7.sort():排序

    lt = [2,3,1]
    lt.sort()
    print(lt) #[1,2,3]
    (lt.sort(key=lambda i:i[1])
    print(lt)#首字母排序)
    

    8.reverse():反转

    lt = [1,2,3]
    lt.reverse()
    print(lt)#[3,2,1]
    

    9.index():获取元素索引

    print(lt.index(2)) #1
    

    10.clear():清空列表

    lt.clear()
    print(lt)
    

    11.copy():复制列表

    lt1 = lt.copy()
    print(lt1)
    

    12.extend():扩展列表

    lt1 = [1,2,3]
    lt2 = [3,4,5]
    lt1.extend(lt2)
    print(lt1) #[1,2,3,3,4,5]
    

    13.remove():移除

    lt.remove(3)
    print(lt) #[1,2]
    

    14.insert():按照索引往前插入值

    lt.insert(0,0.5)
    print(lt) #[0.5,1,2,3]
    

    字典的内置方法

    只能字典使用

    xuan_info_dic = {'name':'1a','height':152,'weight':111,'hobby':['2b','3c','4d']}
    

    1.按key取值/按key修改值/按key增加值

    print(xuan_info_dic['height']) #取值
    
    xuan_info_dic['height']=xuan_info_dic['height']+1
    print(xuan_info_dic['height']) #修改值
    
    xuan_info_dic['age']=30
    print(xuan_info_dic) #增加值
    

    2.成员运算(比较的是key)

    print('age' in xuan_info_dic) #T
    

    3.for循环(对key循环)

    for i in xuan_info_dic:
    	print(i)
    

    4.key()/values()/items()

    print(xuan_info_dic.key()) #所有的key ##dict_keys(['name','height','weight','hobby'])
    print(xuan_info_dic.values()) #所有的值
    ##dict_values(['1a',152,111,['2b','3c','4d']])
    print(xuan_info_dic.items()) #所有的键值对(以列表存储)
    ##dict_items([('name':'1a'),('height':152),('weight':111),('hobby':['2b','3c','4d'])])
    for i in xuan_info_dic.items():
    	print(i[0] + '***' + str(i[1])) #键值对以***相连
    name***1a
    height***152
    ……
    

    5.get():取值

    print(xuan_info_dic.get('height',150))#找到了就找到了;没有值就返回None,如果给定了(150)就算给定的值(150)
    购物车没有的话为1,有的话加1
    shopping_car = {}
    if shopping_car.get('ww'): #如果有的话加1
    	shopping_car['ww'] = shopping_car['ww']+1
    else: #否则直接为1
    	shopping_car['ww']=1
    print(shopping_car)
    

    6.update():扩展字典

    dic1 = {'a':1}
    dic2 = {'b':2}
    dic1.update(dic2)
    print(dic1)#{'a':1,'b':2}
    

    7.setddefault():有则不更改,没有则增加

    dic1 = {'a':1}
    dic1.setdefault('a',2)
    print(dic1) #{'a':1}(因为有a所以不改)
    
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  • 原文地址:https://www.cnblogs.com/793564949liu/p/11437115.html
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