python之路3-元组、列表、字典、集合

1、元组

特点：一旦创建，内容不可修改，又叫只读列表

 a= ('wang','zhang','zhao')
 print(a.count('zhao'))
 print(a.index('wang'))

2、列表

name = ["wang","zhao","zhang"]

　　切片：取多个元素

 name = ["wang","zhao","zhang","lili","hao"]
 print(name[0:3])
 print(name[0:-1])
 print(name[0:])
 print(name[:])
 print(name[::2])
 运行结果：
 ['wang', 'zhao', 'zhang']
 ['wang', 'zhao', 'zhang', 'lili']
 ['wang', 'zhao', 'zhang', 'lili', 'hao']
 ['wang', 'zhao', 'zhang', 'lili', 'hao']
 ['wang', 'zhang', 'hao']

　　追加

name.append('张三')
print(name)
运行结果：
['wang', 'zhao', 'zhang', 'lili', 'hao', '张三']

　　插入

 name.insert(0,'赵四')
 print(name)
 运行结果：
 ['赵四', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']

　　修改

name[0] = 'zhaosi'
print(name)
运行结果：
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']

　　删除

name.remove('zhaosi')
print(name)
运行结果：
['wang', 'zhao', 'zhang', 'lili', 'hao', '张三']

del name[1]
print(name)
运行结果：
['wang', 'zhang', 'lili', 'hao', '张三']

　　扩展

name = ['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']
name1 = ['小明','小张','张三']
print(name)
name.extend(name1)
print(name)

运行结果： 
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三'] 
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三', '小明', '小张', '张三']

　　拷贝

第一层的不会变，后面的跟着变，列表及字典的第一级修改后，copy的内容不会变，下一级的copy值会跟着变，共享空间，指针

print(name)
name1 = name.copy()
print(name1)
name[0]='赵四'
print(name)
print(name1)
运行结果：
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']
['赵四', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']
['zhaosi', 'wang', 'zhao', 'zhang', 'lili', 'hao', '张三']

　　统计

print(name.count('zhang'))

　　排序

name.sort()#正向排序
print(name)
name.reverse()#反向排序
print(name)

　　获取下标

print(name.index('张三'))
运行结果：1

3、字典

特性：无序的；唯一key值，天生去重

student={
    'stu1101':{'name':'张三','age':22},
    'stu1102':{'name':'李四','age':22},
    'stu1103':{'name':'王二','age':25},
}

增加

 student={
     'stu1101':{'name':'张三','age':22},
     'stu1102':{'name':'李四','age':22},
     'stu1103':{'name':'王二','age':25},
 }
 student['stu1104']='王三'
 print(student)
 运行结果：
 {'stu1101': {'name': '张三', 'age': 22}, 'stu1102': {'name': '李四', 'age': 22}, 'stu1103': {'name': '王二', 'age': 25}, 'stu1104': '王三'}

修改

 student={
     'stu1101':{'name':'张三','age':22},
     'stu1102':{'name':'李四','age':22},
     'stu1103':{'name':'王二','age':25},
 }
 student['stu1103']['name']='王三'
 student['stu1101']={'name':'张四','age':23}
 print(student)
 运行结果：
 {'stu1101': {'name': '张四', 'age': 23}, 'stu1102': {'name': '李四', 'age': 22}, 'stu1103': {'name': '王三', 'age': 25}}

删除

pop()：删除指定键值对应的数据

popitem()：随机删除字典中的一对键和值

del student['stu1101']#删除
print(student)
student.pop('stu1101')#删除
print(student)

student.popitem()#随机删除
print(student)

查找

student={
    'stu1101':{'name':'张三','age':22},
    'stu1102':{'name':'李四','age':22},
    'stu1103':{'name':'王二','age':25},
    'stu1105':{'name':'王si','age':26},
    'stu1104':{'name':'王一','age':23},
    'stu1106':{'name':'王sd','age':23},
}
print('stu1101' in student)
print(student['stu1101'])#key不存在会报错
print(student.get('stu1101'))#key不存在返回None
print(student.get('stu1110'))
运行结果：
True
{'name': '张三', 'age': 22}
{'name': '张三', 'age': 22}
None

　　合并更新

student={
    'stu1101':{'name':'张三','age':22},
    'stu1102':{'name':'李四','age':22},
    'stu1103':{'name':'王二','age':25},
    'stu1105':{'name':'王si','age':26},
    'stu1104':{'name':'王一','age':23},
    'stu1106':{'name':'王sd','age':23},
}
student2 = {
    "stu1101":{"name":"wangdawei","age":22,"TEL":1581033},
    "stu1110":"zhaoyazhi"
}
student.update(student2)
print(student)
运行结果：
{'stu1101': {'name': 'wangdawei', 'age': 22, 'TEL': 1581033}, 'stu1102': {'name': '李四', 'age': 22}, 'stu1103': {'name': '王二', 'age': 25}, 
'stu1105': {'name': '王si', 'age': 26}, 'stu1104': {'name': '王一', 'age': 23}, 'stu1106': {'name': '王sd', 'age': 23}, 'stu1110': 'zhaoyazhi'}

其他

print(student.keys())#返回可遍历的KEY值
print(student.values())#返回可遍历的value值
print(student.items())#返回可遍历的KEY，value值

for key in student: 
　　print(key,info[key]) 
 for k,v in student.items(): #会先把dict转成list,数据里大时莫用 
　　print(k,v)

4、集合　

集合是一个无序的，数据不重复的数据组合，作用如下：

• 去重，把一个列表变成集合就自动去重了
• 测试两组数据之间的交集、并集、差集等关系

定义：

a = {1,3,5,7,10}
b = {2,3,4,5,6,8} 

#交集
print(a & b)
print(a.intersection(b))
print(a.intersection_update(b)) #等价于a = a.intersection(b)
print(a)

#差集

a = {1,3,5,7,10} 
b = {1,3,5} 
print(a-b)
print(a.difference(b))
运行结果：
{10, 7}
{10, 7}

#并集

print(a | b)
print(a.union(b))
运行结果：
{1, 2, 3, 4, 5, 6, 7, 8, 10}
{1, 2, 3, 4, 5, 6, 7, 8, 10}

#对称差集

print(a ^ b)
print(a.symmetric_difference(b))#去掉公共部分
运行结果：
{1, 2, 4, 6, 7, 8, 10}
{1, 2, 4, 6, 7, 8, 10}

　　

5、join()函数

join()：    连接字符串数组。将字符串、元组、列表中的元素以指定的字符(分隔符)连接生成一个新的字符串

语法：  'sep'.join(seq)

参数说明
sep：分隔符。可以为空
seq：要连接的元素序列、字符串、元组、字典
上面的语法即：以sep作为分隔符，将seq所有的元素合并成一个新的字符串

返回值：返回一个以分隔符sep连接各个元素后生成的字符串

student={
    'stu1101':{'name':'张三','age':22},
    'stu1102':{'name':'李四','age':22},
    'stu1103':{'name':'王二','age':25},
}
list=['wang','zhao']
print(''.join(list))
print('.'.join(list))
print('.'.join(student))
运行结果：
wangzhao
wang.zhao
stu1101.stu1102.stu1103