开班前自学--python list

Posted 2021-02-11 yingpeng

列表：容器型数据类型

1 读取List

1.1按索引

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
print(l1[0])             # output: front
print(l1[2][1])         # output: cloudpark

1.2 按切片

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
print(l1[1:3])    # output: [‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘]]

2 list 的增

2.1 insert

list.insert(索引，‘添加内容‘）

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.insert(1,‘A MAN CALLED‘)
print(l1)         # [‘front‘, ‘A MAN CALLED‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

 

 2.2 append 追加

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.append(‘Friday‘)
l1.append(‘cloudy‘)
print(l1)    # [‘front‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘, ‘Friday‘, ‘cloudy‘]

 

 用append添加人名单

name_list = [‘huawei‘,‘iphone‘,‘xiaomi‘,‘meizu‘]
while True:
    newname = input(‘请输入名称：按Q或q退出‘).strip().lower()      # 后面加上stripe和lower,去除空格，转换大小写
    if newname == ‘q‘:break                      # 添加中途退出命令
    name_list.append(newname)
    print(‘你已经成功添加添加了% s‘ %newname)       # 此处要用格式化输出
print(name_list)    # input: OPPO  VIVO Q   output:[‘huawei‘, ‘iphone‘, ‘xiaomi‘, ‘meizu‘, ‘oppo‘, ‘vivo‘]

 

 2.3 extend 分解成最小元素添加

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.extend(‘云谷图书馆‘)
print(l1)  # [‘front‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘, ‘云‘, ‘谷‘, ‘图‘, ‘书‘, ‘馆‘]

 

 

3 list 删

3.1 pop——用索引删除后

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.pop(0)           # 删除‘fornt‘
print(l1.pop(0))    # 删除‘ove‘,并返回删除值 
print(l1)           # [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

 

增删改查，只有pop才有返回，其它返回会print：None

3.2 remove——按元素删除

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.remove(‘2019.03.01‘)
print(l1)    # [‘front‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘09:06‘]

 

3.3 clear ——清空列表

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1.clear()            # 只清空不删除
print(l1)             # []

 

3.4 del——删除列表

3.4.1 在内存内删除

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
del l1
print(l1)           # 报错，无法找到l1列表

 

3.4.2 按索引删除

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
del l1[2]
print(l1)           # [‘front‘, ‘ove‘, ‘2019.03.01‘, ‘09:06‘]

3.4.3 按切片删除

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
del l1[0:2]
print(l1)   #[[‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

 

 

4 list 改

4.1 用索引更改

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1[0] = ‘shenzhen‘
print(l1)      # [‘shenzhen‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

4.2 用切片更改

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1[0:1] = ‘shenzhen‘,‘longgang‘     # 切片删除数量不一定要和增加一样，会直接删除并添加
print(l1)           # [‘shenzhen‘, ‘longgang‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

 

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
l1[0:1] = ‘shenzhen‘        # 改的内容为一个字符串时，会拆分再添加
print(l1)           # [‘s‘, ‘h‘, ‘e‘, ‘n‘, ‘z‘, ‘h‘, ‘e‘, ‘n‘, ‘ove‘, [‘library‘, ‘cloudpark‘, ‘CC+‘], ‘2019.03.01‘, ‘09:06‘]

 

5 　　list 查

for

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
for i in l1:
    print(i)     # 分行列出列表内内容

 

6 list 其它操作

6.1  len 列表元素数量

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
cou = len(l1)
print(cou)             # 5

 

6.2 count 元素在列表中的数量

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘,‘ove‘]
print(l1.count(‘ove‘))          # 2

 

6.3 index 通过元素找索引

l1 = [‘front‘,‘ove‘,[‘library‘,‘cloudpark‘,‘CC+‘],‘2019.03.01‘,‘09:06‘]
print(l1.index(‘ove‘,1,4))    # 1  （可以切片查询）

 

6.4 sort 排序

l1 = [1,4,6,8,4,3,9,7,]
l1.sort()         # 列表中元素只能时int，否则报错
print(l1)         # [1, 3, 4, 4, 6, 7, 8, 9]

 

l1 = [1,4,6,8,4,3,9,7,]
l1.sort(reverse = True)         # 倒序
print(l1)         # [9, 8, 7, 6, 4, 4, 3, 1]

 

6.5 reverse

 

l1 = [1,4,6,8,4,3,9,7,]
l1.reverse()         # 反序
print(l1)         # [7, 9, 3, 4, 8, 6, 4, 1]

 

 

7 list 嵌套

7.1  将list中元素大写

# 将‘front‘变为全部大写。
l1 = [‘front‘,‘ove‘,[‘library‘,56,‘cloudpark‘,‘CC+‘,‘16‘,],‘2019.03.01‘,‘09:06‘]
l1[0] = l1[0].upper()
print(l1)              # [‘FRONT‘, ‘ove‘, [‘library‘, 56, ‘cloudpark‘, ‘CC+‘, ‘16‘], ‘2019.03.01‘, ‘09:06‘]

 

7.2  列表嵌套修改

# 将‘cloudpark‘变为首字母大写，并放回原处
l1 = [‘front‘,‘ove‘,[‘library‘,56,‘ cloudpark‘,‘CC+‘,‘16‘,],‘2019.03.01‘,‘09:06‘]
l1[2][2] = l1[2][2].strip().capitalize()
print(l1)           # [‘front‘, ‘ove‘, [‘library‘, 56, ‘Cloudpark‘, ‘CC+‘, ‘16‘], ‘2019.03.01‘, ‘09:06‘]

 

7.3  嵌套int变str

# 将56加10并变为字符串‘65‘
l1 = [‘front‘,‘ove‘,[‘library‘,56,‘ cloudpark‘,‘CC+‘,‘16‘,],‘2019.03.01‘,‘09:06‘]
l1[2][1] = str(l1[2][1] + 10)
print(l1)          # [‘front‘, ‘ove‘, [‘library‘, ‘66‘, ‘ cloudpark‘, ‘CC+‘, ‘16‘], ‘2019.03.01‘, ‘09:06‘]

 

7.4  嵌套内str变int

# ‘16‘变成 10
l1 = [‘front‘,‘ove‘,[‘library‘,56,‘ cloudpark‘,‘CC+‘,‘16‘,],‘2019.03.01‘,‘09:06‘]
l1[2][-1] = int(l1[2][-1]) - 6
print(l1)        # [‘front‘, ‘ove‘, [‘library‘, 56, ‘ cloudpark‘, ‘CC+‘, 10], ‘2019.03.01‘, ‘09:06‘]