Strings, lists, dictionaries, tuples, the sequence structure are set Sequence, by an index, the function includes a slice, you can store any type of data.
List list
Is defined: list = []
list=[1,2,'a',"hello",(3,4),[3,5,'f'],{'a':'tom'}]
1> by:
a> list.append () # default increased tail
list.append (100) list.append ([1,2]) # default increased tail
b> list.insert (subscript insert, insert value) is inserted into a certain position #
list.insert(0,120)
c> Insert sublist
list[-2].insert(1,"edf")
2> Delete:
a> del subscript looking at the value of deleted
del list[1]
del list[0:2]
b> list.pop (): returns a value, delete the return value of that element
list.pop(2)
c> list.remove () #: value delete, delete the slowest, because to traverse to find this value
list.remove(2)
3> change
list [0] = 20 # subscript Review
4> check
list [3] # subscript Find
Merge list: +, extend ()
a = [1,2] b = [3,4]
a> + temporary combined, save as equivalent
print (a + b) - - [1,2,3,4]
b> permanently merge - expanded list
print (a.extend (b)) - - - - a result: [1,2,3,4]
Built-in functions:
len (list): calculated number of elements
max (list): Returns the maximum element of the list
min (list): Returns the list of the minimum element
list.reverse (): Reverse elements in the list
list.remove (obj): remove the list a value of the first match
The first element and the last element:
str [0], p [referred to as (p) -1]
p [-1], p [-I (p)]
Tuple tuple: can not be modified, the value of the element can not be modified, the number can not be modified, corresponding to fixed
1> sequence is also a sequence
2> can store any type of data
3> also has a function sections
4> different tuples and lists: the list of tuples its constituent elements can
5> only query can not be CRUD
Tuples and lists differences:
Dictionary dict
1> defined
Key-value pair dic = { 'key': 'value', 'key': value}
Key: can be: a string (common), int, float, tuple, bool
Not: list, dict
Value: Any type
dict1 = {}
dict2 = {'name'：mike，'age'：28}
2> Features
Sequence sequence, called characteristic map, dictionaries are unordered, look for clear, scalability, and looking through the key values
3> common method
a> by:
The dictionary is the only key;
A dictionary is unordered;
python3: Tail increase python2: random increase
If the key name exists - modify operations;
If the key name does not exist --- New;
dict['weight'] = 170
b> deleted:
del : del dict['name']
pop : dict.pop('age')
c> 改：
通过键进行修改;
dict ['name'] = 'mike'; (如果键存在，则修改值；如果键不存在，则新增键值对)
d> 查：
通过键去找值;
如果键不存在-报错-keyerror;
print (dict['name']);
4> 常用操作
a> 判断键是否在字典中，in
print ('name' in dict) - -- - True
b> 清空字典内容clear()
清空 : dict.clear()
重新复制 : dict = {}
c> 长度len(dict)
len(dict)
len(dict['name']) #len(dict['键名'])
d> 返回所有的键keys()
dict.keys() - - 类列表，不能使用下标，但可以遍历
如果一定要使用下标，则需要将其转换为列表list
list(dict.keys())[0] tuple(dict.keys())[0]
e>返回所有的值values()
dict.values()
f> 返回所有的键值对items()
dict.items() - - [(’键’，‘值‘),(’键’，‘值‘)]
print(dict.items()) -- [('name','Jack'),('age',21)]
g> 字典合并update()
d={1:'1',2:'2'}
print(d.update({4:'4',5:'5'}))
结果： {1：’1‘，2：’2‘，3：’3‘，4：’4‘，5：‘5’}
h> 字典的遍历操作
1) for one in dict: # one取得是键
print (one)
-- name
age
2) for one in dict:#获取键值
print(one,dict[one])
-- name tom
age 21
3) for a,b in dict.items():
print(a,b)
-- name tom
age 21
5> 使用场景
有序场景不能用;
鉴定函的存储可以使用列表;
可以作为扩展内容;