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python-基础 列表 集合 字典 文件处理
目录
- 列表、元组操作
- 字典操作
- 集合操作
- 文件操作
1.列表、元组操作
列表是最常用的数据类型之一，通过列表可以对数据实现最方便的存储、修改等操作
定义列表
names = ["张三","李四","王麻子"]
通过下标取列表中的数据.下标按0开始计算
names = ["张三","李四","王麻子"] print(names[0]) 张三 print(names[1]) 李四 print(names[2]) 王麻子 注意:也可以倒着取 print(names[-3]) 张三 print(names[-2]) 李四 print(names[-1]) 王麻子
切片:取多个元素(顾头不顾尾.不取尾)
names = ["张三","李四","王麻子","疯子","傻子"] print(names[0:2]) [‘张三‘, ‘李四‘] print(names[:3]) [‘张三‘, ‘李四‘, ‘王麻子‘] print(names[1:]) [‘李四‘, ‘王麻子‘, ‘疯子‘, ‘傻子‘] print(names[0::2]) [‘张三‘, ‘王麻子‘, ‘傻子‘] print(names[::2]) [‘张三‘, ‘王麻子‘, ‘傻子‘]
追加(在最后一位增加)
names = ["张三","李四","王麻子","疯子","傻子"]
names.append("SB")
print(names)<br>[‘张三‘, ‘李四‘, ‘王麻子‘, ‘疯子‘, ‘傻子‘, ‘SB‘]
插入(随便在什么地方插入)
names = ["张三","李四","王麻子","疯子","傻子"] names.insert(2,"老寒腿") names.insert(5,"大脚") print(names) [‘张三‘, ‘李四‘, ‘老寒腿‘, ‘王麻子‘, ‘疯子‘, ‘大脚‘, ‘傻子‘, ‘SB‘]
修改
names = ["张三","李四","王麻子","疯子","傻子"]
names[2] = ("麻子")
print(names)
[‘张三‘, ‘李四‘, ‘麻子‘, ‘疯子‘, ‘傻子‘]
删除
#指定删除下标对应的
names = ["张三","李四","王麻子","疯子","傻子"]
del names[4]
print(names)
[‘张三‘, ‘李四‘, ‘王麻子‘, ‘疯子‘]
#使用remove删除时只能删除第一个出现的
names = ["张三","李四","李四","王麻子","疯子","傻子"]
names.remove("李四")
print(names)
[‘张三‘, ‘李四‘, ‘王麻子‘, ‘疯子‘, ‘傻子‘]
#使用pop删除时删除列表中的最后一个值
names = ["张三","李四","李四","王麻子","疯子","傻子"]
names.pop()
print(names)
[‘张三‘, ‘李四‘, ‘李四‘, ‘王麻子‘, ‘疯子‘]
拷贝(此处的拷贝是浅拷贝.意思是只拷贝第一层)
names = ["张三","李四","李四","王麻子","疯子","傻子"] names_copy = names.copy() print(names_copy) [‘张三‘, ‘李四‘, ‘李四‘, ‘王麻子‘, ‘疯子‘, ‘傻子‘]
统计
names = ["张三","李四","李四","王麻子","疯子","傻子"]
print("李四出现次数:",names.count("李四"))
李四出现次数: 2
排序
names = ["张三","李四","李四","王麻子","疯子","傻子","3","2"] names.sort() print(names) [‘2‘, ‘3‘, ‘傻子‘, ‘张三‘, ‘李四‘, ‘李四‘, ‘王麻子‘, ‘疯子‘]
#3.0里不同数据类型不能放在一起排序了
获取下标
names = ["张三","李四","李四","王麻子","疯子","傻子","1","3","2"]
print("李四的下标是:",names.index("李四"))
李四的下标是: 1 <br>#只返回找到的第一个下标
2.字典操作
字典一种key - value的数据类型。
K怎么定义调用的时候就得怎么调用。
key 定义规则：1.不可变：数字，字符串，元组（可变：列表，字典）。K 唯一(如果K定义重复那么取的时候只取最后一次出现的)
v 定义规则：任意类型
字典：定义符号（），与列表完全一致，唯一不同的是元组内元素不可变
语法:
dic = {name:"Yuhl",age=18,QQ=2878****}
特性：无序
Key必须唯一.
增加
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
dic["Phone"] = "110"
print(dic) #增加
{‘Phone‘: ‘110‘, ‘age‘: ‘18‘, ‘QQ‘: ‘2878****‘, ‘name‘: ‘Yuhl‘}
dic00 = {"name":{"Yuhl":{"age","QQ"},"QQ":"111"},"age":18}
dic00.setdefault("gender","zhang") #增加，随机
print(dic00)
修改
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
dic ["name"] = "Yuhonglin"
print(dic) 注意:K值无法进行修改.只能修改value
{‘QQ‘: ‘2878****‘, ‘age‘: ‘18‘, ‘name‘: ‘Yuhonglin‘}
dic00 = {"name":{"Yuhl":{"age","QQ"},"QQ":"111"},"age":18}
dic00.update(name="YUHONGLIN",gender="name") #修改和新增
print(dic00)
{‘age‘: 18, ‘gender‘: ‘name‘, ‘name‘: ‘YUHONGLIN‘}
删除
#删除
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
del dic["name"]
print(dic)
{‘QQ‘: ‘2878****‘, ‘age‘: ‘18‘}
#标准删除
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
dic.pop("name")
print(dic)
{‘age‘: ‘18‘, ‘QQ‘: ‘2878****‘}
#随机删除
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
dic.popitem()
print(dic) 多试几次有效果
查找
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
print("打印结果是:",dic.get("name")) #获取
打印结果是:Yuhl
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
print("打印结果是:",dic["name"]) #与之前的一样
打印结果是:Yuhl
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
print("打印结果是:","stu1102" in dic)
打印结果是:False #在字典中有返回True否则返回False
dic = {"name":"Yuhl","age":"18","QQ":"2878****"}
print("打印结果是:",dic["stu1105"]) #如果一个key不存在会报错. get不会直接返回None
其他方法:
dic00 = {"name":"Yuhl","age":18}
dic00.clear() #清空
print(dic00)
答应出来的信息是:{}
dic00 = {"name":{"Yuhl":{"age","QQ"},"QQ":"111"},"age":18}
dic000002= dic00.fromkeys(["a","b"],1) #快速生成字典
print(dic000002)
自动生成的字典是: {‘b‘: 1, ‘a‘: 1}
dic00 = {"name":{"Yuhl":{"age","QQ"},"QQ":"111"},"age":18}
for k,v in dic00.items():
print(k,v) #列表打印
print(k[0],v) #列表打印
dic000 = {"name":"Yuhl","age":18,"QQanddianhua":[110,133]}
dic00new = dic000.copy() #拷贝.浅拷贝
print(dic00new,"\n",dic000)
dic00 = {"name":{"Yuhl":{"age","QQ"},"QQ":"111"},"age":18}
dic00["QQanddianhua"]="11222","111111" #拷贝
print("\n",dic00)
{‘age‘: 18, ‘QQanddianhua‘: (‘11222‘, ‘111111‘), ‘name‘: {‘QQ‘: ‘111‘, ‘Yuhl‘: {‘age‘, ‘QQ‘}}}
3、集合
作用:去重复 和 关系运算(集合分别有:交集、差集、并集)其他方法:
#交集
python_set = {"alex","lhf","zhangsan","lisi","wangmazi"}
linux_set = {"alex","lhf","Yuhl","dsd"}
print(python_set&linux_set) #求两个集合里面出现相同的数
print(python_set.intersection(linux_set))
print(python_set&linux_set)
print(python_set.intersection(linux_set))
：{‘lhf‘, ‘alex‘}
：{‘lhf‘, ‘alex‘}
：{‘lhf‘, ‘alex‘}
：{‘lhf‘, ‘alex‘}
python_set = {"alex","lhf","zhangsan","lisi","wangmazi"}
linux_set = {"alex","lhf","Yuhl","dsd"}<br>
#并集
print(python_set|linux_set) #去重复
print(python_set.union(linux_set)) #去重复
：{‘lhf‘, ‘Yuhl‘, ‘dsd‘, ‘alex‘, ‘wangmazi‘, ‘lisi‘, ‘zhangsan‘}
：{‘lhf‘, ‘Yuhl‘, ‘dsd‘, ‘alex‘, ‘wangmazi‘, ‘lisi‘, ‘zhangsan‘}
# #差集
python_set = {"alex","lhf","zhangsan","lisi","wangmazi"}
linux_set = {"alex","lhf","Yuhl","dsd"}
print(python_set-linux_set) #去掉重复的
print(python_set.difference(linux_set))
print(linux_set-python_set) #去掉重复的
print(linux_set.difference(python_set))
{‘lisi‘, ‘zhangsan‘, ‘wangmazi‘}
{‘dsd‘, ‘Yuhl‘}
#并集
python_set = {"alex","lhf","zhangsan","lisi","wangmazi"}
linux_set = {"alex","lhf","Yuhl","dsd"}
print(python_set|linux_set) #去重复(将两个重复数据打印出来.合并在一起)
print(python_set.union(linux_set)) #去重复(将两个重复数据打印出来.合并在一起)
#d对称差集
python_set = {"alex","lhf","zhangsan","lisi","wangmazi"}
linux_set = {"alex","lhf","Yuhl","dsd"}
print(python_set^linux_set)#把共有的地方去掉就是对称差集
print(python_set.symmetric_difference(linux_set))
：{‘lisi‘, ‘dsd‘, ‘zhangsan‘, ‘wangmazi‘, ‘Yuhl‘}
：{‘lisi‘, ‘dsd‘, ‘zhangsan‘, ‘wangmazi‘, ‘Yuhl‘}
s1 = {1,2,3,4,5}
s2 = {2,3}
#子集
print(s1 <= s2) #s2是s1的子集
print(s1.issubset(s2))
#父集
print(s2 <= s1) #s1是s2的父集
print(s1.issuperset(s2))
s3 = set(["he","l","1","1",1,2,3])
print(s3)
其他方法:
#更新
s1 = {1,2,3}
s2 ={"YHL"}
s1.update(‘e‘) #插入
s1.update((1,2,3,4,5)) #去重进行写入
s1.update("hello")
s1.update(s2)
print(s1)
#增加
s1 = {1,2,3}
s1.add("Hello") #整个加入
print(s1)
#删除
s3 = {1,2,3,4,5,6,7,8,9,10}
s3.pop()
print(s3) #随机删除
s3.remove(10) #指定删除 如果没有会报错
print(s3)
s3.discard("a") #不报错的删除 没有也不会报错.有不会报错
print(s3,"------")
4.文件处理
python-基础 列表 集合 字典 文件处理
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