【python】元组和字典你真的懂了吗？字典和列表你真的分清了么？

In [1]: a= 1,2,3

In [2]: a

Out[2]: (1,2,3)

In [3]: type(a)

Out[3]:tuple

In [4]: b=(1,2,3)

In [5]: b

Out[6]: (1, 2, 3)

In [7]: type(b)

Out[7]:tuple

In [8]: a= ()

In [9]: type(a)

Out[10]: a

In [11]: ( )

Out[11]:tuple

In [12]: a= (2)

In [13]: a

Out[13]: 2

In [14]: type(a)

Out[14]:int

In [15]: a= (2,)

In [16]: a

Out[16]: (2,)

In [17]: type(a)

Out[17]:tuple

In [18]: a= 2

In [19]: a

Out[19]: 2

In [20]: a=2,

Out[20]: (2,)

可存放的数据类型：数字（整型）、字符串、元组嵌套类型、元组嵌套列表、元组嵌套字典

In [21]: a= (11，22，33，11，22，11，11)

In [22]: a[2]

Out[22]: 33

In [23]: b.count(11)

Out[23]:4

In [24]: b.index(33)

Out[24]: 2

In [25]: name= [‘小鹏’，’凉凉’，’卷妹’，’吕布’，’貂蝉’，’黑客’，’魏延’]

In [26]: atuple=tuple(names)

In [27]:atuple

Out[27]: (‘小鹏’，’凉凉’，’卷妹’，’吕布’，’貂蝉’，’黑客’，’魏延’)

In [28]: alist=list(atuple)

In [29]: alist

Out[29]: [‘小鹏’，’凉凉’，’卷妹’，’吕布’，’貂蝉’，’黑客’，’魏延’]

In [30]: chool_names = (('北京大学', '清华大学'),('南开大学', 'CSDN大学'),('贵州大学', '青海大学'))

In [31]: chool_names[1][1]

Out[32]: ‘CSDN大学’

变量student为字典类型：

student= {'name':' 小鹏', 'id':100, 'sex':' 男', 'address':' 中国’}

In [2]: student['name']

Out[2]: '小鹏'

In [3]: student['adress']

----------------------------------------------------------------------

KeyError                          Traceback (most recent call last)

in

----> 1 student['adress']

KeyError: 'adress'

In [4]: student.get("address")

In [5]: student.get("id")

Out[5]: 100

In [6]: student.get("id",19)

Out[6]: 19

student = {"name":"小鹏","id":100,"sex":"男"}

print("修改前的内容：",student)

student["id"] = 30

print("修改之后：",student)

修改前的内容： {'name': '小鹏', 'id': 100, 'sex': '男'}

修改之后： {'name': '小鹏', 'id': 30, 'sex': '男'}

student = {"name":"小鹏","id":100,"sex":"男"}

print("增加前的内容：",student)

student["local"] = "北京"

print("增加之后：",student)

增加前的内容： {'name': '小鹏', 'id': 100, 'sex': '男'}

增加之后： {'name': '小鹏', 'id': 100, 'sex': '男', 'local': '北京'}

1.

 del删除指定的元素

student = {"name":"小鹏","id":100,"sex":"男"}

del student["id"]

print(student)

2.

del删除整个字典

del student

print(student)

3.

clear清空整个字典

student.clear()

print(student)

4.

pop删除字典指定元素并且得到值

result = student.pop("name")

print(student)

print(result)

5.

popitem随机返回并删除字典中的一对键和值(项）(字典没有顺序所以是随机，实际是从后往前删)

a,b = student.popitem()

print(student)

print(a,b)

info = {"name":"小鹏","id":100,"sex":"男","age":30}

1.普通获取数据方式

简写

print(info["name"])

print(info.get("name","无名"))

完整

name = info["name"]

print(" 使用[key]=",name)

name = info.get("name")

print(" 使用get(key) 查找=",name)

2.通过Key查找数据           #info和info.keys效果是一样的（只不过info隐藏了）

if "name" in info:

    print("使用in根据key从字典中查找name是存在的。")

if "name" in info.keys():

    print("使用in根据key从字典中的info.keys()查找name是存在的")

3.通过Value获取值

if "小鹏" in info.values():

    print("使用in根据'值'从字典中查找info.values（）小鹏是存在的。")

In [1]: info = {"name":"小鹏","id":100,"sex":"男","age":30}

In [2]: len(info)

Out[2]: 4

In [3]: info.keys()

Out[3]: dict_keys(['name', 'id', 'sex', 'age'])

In [4]: info.values()

Out[4]: dict_values(['小鹏', 100, '男', 30])

In [5]: info.items()

Out[5]: dict_items([('name', '小鹏'), ('id', 100), ('sex', '男'), ('age', 30)])

字符串遍历

列表遍历

元组遍历

a_str = "hello atguigu"

for a in a_str:

print(a)

a_list = [" 刘备", 2, [" 曹 *** "," 曹丕"], "孙权", 5]

for a in a_list:

print(a,end=" ")

print("")

a_tuple = (" 曹 *** ", " 刘备", 3, 4, 5)

for a in a_tuple:

print(a,end=" ")

print("")

遍历字典的key（键）

name = {"name":"小鹏","id":100,"sex":"男","age":30}

for key in name.keys():

    print(key)

for value in name.values():

    print(value)

for ite in name.items():

    print(ite)

遍历字典的key-value（键值对）

for key,value in name.items():

    print(key,value)

names = [" 小鹏"," 几何心凉"," 貂蝉"]

for i in range(len(names)):

print("%d %s "% (i,names[i]))

names = [" 小鹏"," 几何心凉"," 貂蝉"]

for index,value in enumerate(names):

print("%d %s " % (index,value))

names = [" 小鹏"," 几何心凉"," 貂蝉"]

for index,value in enumerate(names,2):   #2从第几个开始

print("%d %s " % (index,value))

infos = {'name':' 小鹏', 'id':100, 'sex':' 男生', 'address':' 中国北京'}

for index,value in enumerate(infos):

print("%d %s " % (index,value))

infos = {'name':' 小鹏', 'id':100, 'sex':' 男生', 'address':' 中国北京'}

for index,value in enumerate(infos.values()):

print("%d %s " % (index,value))