4.3 数据类型内置方法_可变类型(1)_列表

4.3 数据类型内置方法_可变类型(1)_列表

4.3.1 列表类型

1. 作用：存多个元素，如商品名称，身高等。
2. 定义方式：[]内用逗号隔开，存储任意类型元素。

name_list=['coco','mike','jarry']
name_list=list(['coco','mike','jarry'])
str_list=list('coco') #类型转换
print(str_list)

['c', 'o', 'c', 'o']

3.方法

• 方法1 ***

# （1）按索引取值（正向取值+反向取），可存可取
name_list=['coco','mike','jarry','jane','lihua','wangmei']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')
#取值
#按索引取值
print(name_list[1])
print(name_list[-1])
#切片取值
print(name_list[::2]) #正向取值，步长为2
print(name_list[::-1]) #逆向取值

#赋值
name_list[0]='xiaoming' #'xiaoming'替换索引0位置原来的值
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236768512,name_list:['coco', 'mike', 'jarry', 'jane', 'lihua', 'wangmei']
mike
wangmei
['coco', 'jarry', 'lihua']
['wangmei', 'lihua', 'jane', 'jarry', 'mike', 'coco']
['xiaoming', 'mike', 'jarry', 'jane', 'lihua', 'wangmei']
操作后：id:1756236768512,name_list:['xiaoming', 'mike', 'jarry', 'jane', 'lihua', 'wangmei']

#(2)切片
#list[index1:index2:step]
name_list=['coco','mike','jarry','jane','lihua','wangmei']

print(name_list[1])
print(name_list[-1])
print(name_list[::2]) #正向取值，步长为2
print(name_list[::-1]) #逆向取值

mike
wangmei
['coco', 'jarry', 'lihua']
['wangmei', 'lihua', 'jane', 'jarry', 'mike', 'coco']

#(3)成员运算
# in /not in
name_list=['coco','mike','jarry','jane','lihua','wangmei']

print('coco' in name_list)
print('coco' not in name_list)

True
False

#(4)追加，在列表后加入值
# .append()
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

print(name_list.append('lihua'))
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236226432,name_list:['coco', 'mike', 'jarry']
None
['coco', 'mike', 'jarry', 'lihua']
操作后：id:1756236226432,name_list:['coco', 'mike', 'jarry', 'lihua']

#（5）删除del
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

del name_list[-1]
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236766720,name_list:['coco', 'mike', 'jarry']
['coco', 'mike']
操作后：id:1756236766720,name_list:['coco', 'mike']

# (6)循环
name_list=['coco','mike','jarry']
for i in name_list:
    print(i)

coco
mike
jarry

• 方法2 **

# (1)insert(index,object),在index位置前插入object值
name_list=['coco','mike','jarry']
print(f'操作前·：id:{id(name_list)},name_list:{name_list}')

name_list.insert(1,'lihua')
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前·：id:1756236771264,name_list:['coco', 'mike', 'jarry']
['coco', 'lihua', 'mike', 'jarry']
操作后：id:1756236771264,name_list:['coco', 'lihua', 'mike', 'jarry']

# (2)pop(index),删除指定索引元素，不指定索引默认删除尾部元素
#索引不存在报错
name_list=['coco','mike','jarry']
print(f'操作前·：id:{id(name_list)},name_list:{name_list}')

name_list.pop()
print(name_list)
name_list.pop(0)
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前·：id:1756236768576,name_list:['coco', 'mike', 'jarry']
['coco', 'mike']
['mike']
操作后：id:1756236768576,name_list:['mike']

# (3)remove,删除指定值元素
# 指定值在列表中不存在则报错
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

name_list.remove('coco')
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236764928,name_list:['coco', 'mike', 'jarry']
['mike', 'jarry']
操作后：id:1756236764928,name_list:['mike', 'jarry']

# (4)count()，计数
name_list=['coco','mike','jarry','coco']

print(name_list.count('coco'))

2

# (5)index,获取指定元素索引但是只会获取值第一个出现位置
name_list=['coco','mike','jarry']

print(name_list.index('mike'))

1

# (6)clear,清空列表
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

print(name_list.clear())

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236762880,name_list:['coco', 'mike', 'jarry']
None
操作后：id:1756236762880,name_list:[]

# (7)copy,复制
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')
name1=name_list.copy()
print(name1)
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236767296,name_list:['coco', 'mike', 'jarry']
['coco', 'mike', 'jarry']
['coco', 'mike', 'jarry']
操作后：id:1756236767296,name_list:['coco', 'mike', 'jarry']

# (8)extend(列表类型)，把extend内的列表元素逐一添加到原列表中
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

name_list.extend(['lihua','Jane'])
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236767616,name_list:['coco', 'mike', 'jarry']
['coco', 'mike', 'jarry', 'lihua', 'Jane']
操作后：id:1756236767616,name_list:['coco', 'mike', 'jarry', 'lihua', 'Jane']

# (9)reverse,反转列表
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

name_list.reverse()
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236771264,name_list:['coco', 'mike', 'jarry']
['jarry', 'mike', 'coco']
操作后：id:1756236771264,name_list:['jarry', 'mike', 'coco']

# (10)sort,排序按照字母从大到小排序
name_list=['coco','mike','jarry']
print(f'操作前：id:{id(name_list)},name_list:{name_list}')

name_list.sort()
print(name_list)

print(f'操作后：id:{id(name_list)},name_list:{name_list}')

操作前：id:1756236767296,name_list:['coco', 'mike', 'jarry']
['coco', 'jarry', 'mike']
操作后：id:1756236767296,name_list:['coco', 'jarry', 'mike']

4. 存储一个值或多个值：多个值
5. 有序 or 无序：有序
6. 可变or不可变：可变