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  • 029 列表类型内置方法

    一、列表类型内置方法(list)

    1. 用途:

    ​ 描述多个值,比如爱好

    2. 定义方式:

    ​ []内可以有多个任意类型的值,逗号分隔元素

    3. 内置方法:

    3.1 优先掌握

    1. 按索引取值(正向取值+反向取值),即可存也可以取
    2. 切片
    3. 长度len
    4. 成员运算in和not in
    5. 追加append
    6. 删除del
    7. 循环

    1.按索引取值(正向取值+反向取值),即可存也可以取

    print(f"{'索引取值':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    print(1, hobby_list[1])
    hobby_list[-1] = '233'  # 索引修改
    print(2, hobby_list[-1])
    

    ------------------------------------------------索引取值------------------------------------------------
    1 swimming
    2 233

    2.切片

    print(f"{'切片':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    print(hobby_list[:])  # ['play', 'swimming', 'dancing', '666']
    print(hobby_list[::-1])  # 从右到左  # ['666', 'dancing', 'swimming', 'play']
    

    -------------------------------------------------切片-------------------------------------------------
    ['play', 'swimming', 'dancing', '666']
    ['666', 'dancing', 'swimming', 'play']

    3.长度

    print(f"{'长度':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    print(len(hobby_list))
    

    -------------------------------------------------长度-------------------------------------------------
    4

    4.成员运算in和not in

    print(f"{'in/not in':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    print('play' in hobby_list)  # True
    

    ---------------------------------------------in/not in----------------------------------------------
    True

    5.append 追加值

    print(f"{'append()追加':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    hobby_list.append('dapao-->piao')
    print(hobby_list)
    

    ---------------------------------------------append()追加---------------------------------------------
    ['play', 'swimming', 'dancing', '666', 'dapao-->piao']

    6.删除

    print(f"{'del删除':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    del hobby_list[-1]
    print(hobby_list)
    

    -----------------------------------------------del删除------------------------------------------------
    ['play', 'swimming', 'dancing']

    7.for循环

    print(f"{'for 循环':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    for hobby in hobby_list:
        print(hobby)
    print()
    lt = [[1, 2, 3], [2, 3, 4], [5, 6, 7]]	# 使用解压缩方式循环
    for a, b, c in lt:
        print(a, b, c)
       
    

    play
    swimming
    dancing
    666

    1 2 3
    2 3 4
    5 6 7

    3.2 需要掌握

    1. insert 插入
    2. pop 删除(按索引)
    3. remove 移除(按值)
    4. count 计数
    5. index 索引
    6. clear 清空
    7. copy 拷贝
    8. extend 扩展列表
    9. reverse 反转列表
    10. sort 排序

    1.insert() 插入

    print(f"{'insert插入':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    hobby_list.insert(0, '1')  # 插入
    print(hobby_list)
    

    2.pop 删除(按索引)

    print(f"{'pop 删除(按索引)':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    hobby_list.pop()  # 删除,默认删除最后一个
    print(hobby_list)
    

    3.remove 移除(按值)

    print(f"{'remove 移除(按值)':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666']
    hobby_list.remove('666')  # 移除
    print(hobby_list)
    

    4.count 计数

    print(f"{'count 计数':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', '666', 666, '666']
    print(hobby_list.count('666'))  # 对列表内的某一个元素计数)
    

    5.index 索引

    print(f"{'index 索引':-^100}")
    hobby_list = ['play', 'swimming', 'dancing', 'play', '666', 666, '666']
    print(hobby_list.index('play'))  # 索引
    print(hobby_list.index('play', 2, 4))  # 索引2-4内有没有该值
    

    6.clear 清空

    print(f"{'clear 清空':-^100}")
    hobby_list.clear()  # 清除
    print(hobby_list)
    

    7.copy 拷贝

    print(f"{'copy 拷贝':-^100}")
    hobby_list2 = hobby_list.copy()  # 复制列表
    print(hobby_list2)
    

    8.extend 扩展列表

    print(f"{'extend 扩展列表':-^100}")
    hobby_list.extend([1, 2, 3, 4])  # 扩展列表  # ctrl+鼠标左键
    print(hobby_list)
    

    9.reverse 反转列表

    print(f"{'reverse 反转列表':-^100}")
    hobby_list.reverse()  # 反转
    print(hobby_list)
    

    10.sort排序

    print(f"{'sort排序':-^100}")
    hobby_list.sort() 	#排序
    print(hobby_list)
    

    4. 存一个值还是多个值:

    多个值

    5. 有序or无序:

    有序

    6. 可变 or 不可变(重点 可变:值变id不变,不可哈希| 不可变:值变id也变,可哈希):

    可变

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  • 原文地址:https://www.cnblogs.com/XuChengNotes/p/11303730.html
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