Python Data type details

Python data type: int, string, float, Boolean

mutable variables: List

Immutable variables: string, tuple tuple

1.list

List is lists, array, arrays

The list is based on the subscript (0123), and the subscript is also called index, corner label, number

New_stus =[' Andy Lau ', ' Carina Lau ', ' Sun Li ', ' Fan Bingbing ']

The first element subscript is 0, the last subscript is-1, which means 0 is Andy Lau, 1 is Fan Bingbing

Print (New_stus[0]) print (new_stus[-1])
Increase:

Append is to add an element at the end of the list

Citys=[]citys.append (' Beijing ')

Insert can add elements at a specified position (subscript), 0 is the No. 0 position

Citys.insert (0, ' Shanghai ')

By deleting:

Pop Delete an element, delete-1 is the last element to delete

Citys.pop (-1)

Remove deletes the specified element

Citys.remove (' Beijing ')

Clear is clear

Citys.clear () #清空print (citys)

Del deletes the specified position element

Del Citys[-1]print (Citys)

Modified: Modified by subscript

citys[0]= ' Nanjing ' #修改的时候, if the specified subscript does not exist, will be an error

Check:

Print (Citys[0]) #指定位置print (Citys.index (' BJ ')) #获取元素的下标, if the element is not found, it will error print (Citys.count (' BJ ') #获取元素的数量print ( Citys.reverse ()) #就是把list字符串反转一下, but nothing returned print (citys)

List Loop value:

#list循环lists1 = [' Andy Lau ', ' Fan Bingbing ', ' Nicholas Tse Feng ', ' Faye Wong ', ' Li Bingbing ', [11,33,6,7]]for name in Lists1:    if Type (name) ==list: for        i in Name: Print            (i)    print (name)

2. Dictionaries

Dictionaries are key--value forms, dictionaries are unordered.

The dictionary both uses in to judge whether the key exists

Advantages: 1. Easy access to data

2. Fast speed

Infos = {    ' name ': ' Andy Lau ',    ' sex ': ' Male ',    ' addr ': ' Hong Kong ',    ' age ': 18}

Check:

Get

Print (Infos.get (' name ')) print (Infos.get (' II ')) #如果ii取不到, which is Noneprint (' II ') #如果ii取不到, specify the value as 110

Brackets []

Print (infos[' name ')) print (infos[' ee ')

Increase:

infos[' phone ']=1242132556 #增加一个keyinfos. SetDefault (' girlfriend ', ' hehe hey ') # key Valueinfos.setdefault (' name ', ' Nicholas Tse Feng ') # The value cannot be modified if key exists

Modify:

infos[' name ']= ' Nicholas Tse Front ' #如果key存在的话, you can modify the value

Delete:

Pop Delete specified key

Infos.pop (' name ') #指定key删除

Popitem Random Deletion

Infos.popitem () #随机删除一个key

Del Delete the specified key

Del infos[' phone '] #指定key来删除

Clear Empty Dictionary

Infos.clear () #清空字典

Method:

Get the key/value of a dictionary

Print (Infos.values ()) #获取到字典所有的valueprint (Infos.keys ()) #获取到字典所有的keyprint (Infos.items ()) #获取到字典多有k-V

3. Tuples

If there is only one element in the tuple, then you must add a comma behind the element

T= (, ' e ', ' a ')

Print type

Print (Type (t))

Find the element subscript

Print (T.index (2)) #找到元素的下标

Number of elements to find

Print (T.count (2)) #找到元素的个数

4. Slicing

A slice is a type of French that lists the values, and the same applies to strings, where they are concatenated with colons

Print (Nums[1:3]) #切片定义: Want to take a number of values from the list  Gu Tou regardless of the tail  1 means that the print (nums[1:]) from position 1, the end of the end, the end can not write print (nums [: 2]) #如果从头开始去, take to the end of one of the following subscript, then the beginning can not write print (nums[:]) #取到所有

Lis cast to List

# lis = List (range (1,21)) print (LIS) print (lis[:11]) print (Lis[:11:2]) #2是步长 means to take one  time from  the default if the step is a positive number Left-to-right value print (Lis[:11:-1]) #步长是 1 If the step is negative from right to left

List reversal

Lis.reverse () #反转, changes the value of list new_list = Lis[::-1]print (lis[::-1]) #反转, produces a new list, does not change the original value

Python Data type details