[class, abstraction and inheritance]

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Personal Nickname ：lxw-pro
Personal home page ： Welcome to your attention My home page
Personal perception ： “ Failure is the mother of success ”, This is the same truth , Sum up in failure , Grow in failure , To be IT A generation of masters in the world .

Class creation

init() Method — The function is to assign values to the attributes of objects

• The syntax for accessing attributes is ： Object name . Property name
• The syntax of the access method is ： Object name . Method name

in application , You can instantiate multiple objects in the same way

#  Create a class Bird
class Bird:
    def __init__(self, n, c, s):
        self.name = n
        self.color = c
        self.size = s

        self.age = 1

    #  Define methods get_description, Parameter is self, Auto in 
    def get_description(self):
        description = f'{
      self.name}{
      self.color}{
      self.size}'
        print(description)

    def get_age(self):
        print(f"This bird is {
      self.age}")

#  Change the value of the attribute through methods ：

    def update_age(self, a):
        self.age = a


#  Instantiate objects my_bird, by my_bird Attribute ' Parrot ', ' green ', ' medium-sized '
my_bird = Bird(' Parrot ', ' green ', ' medium-sized ')
my_bird.get_description()

my_bird.get_age()

your_bird = Bird(' The sparrow ', ' gray ', ' medium-sized ')
print(f"Your bird's name is {
      my_bird.name}")
your_bird.get_description()
#  By accessing method statements  my_bird.get_description(), Successful execution of method  get_description()  Print statements in 

print(f"My bird's name is {
      my_bird.name}")
print(f"My bird's color is {
      my_bird.color}")

#  Set default values for properties 

#  Modify attribute values directly , Statement for ： Object name . Property name  =  value 
my_bird.age = 3
my_bird.get_age()

my_bird.update_age(5)
my_bird.get_age()

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Simple class creation

class Musician:    #  Create a class 
    glasses = " sunglasses "   #  Create class properties 

    def __init__(self, city):  #  Create initialization method 
        self.city = city      #  Assignment properties 
        print(' In organizational language ……')

    def intr(self):      #  Create class methods 
        print(' I come from %s' % self.city)


gz = Musician(' Guizhou, China ')  #  Class instantiation object 
print(gz.glasses)
gz.intr()   #  Calling class methods 

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Object Is the parent of all classes , Call it The root class i
sinstance() Function to determine Whether an instance belongs to a class

The relevant code is as follows ：

class Car:
    wheel = 4

    def run(self):
        print(' Yes %d A wheel , Can drive fast ' % self.wheel)


class BMW(Car):
    pass        # pass Express ' skip ', Do nothing else 


BMW320 = BMW()
print(BMW320.wheel)     #  Running results ：4
BMW320.run()            #  Running results ： Yes 4 A wheel , Can drive fast 

BENZ600 = Car()  #  Use Car Class to create Benz 600
BMW320 = BMW()   #  Use BMW Class creation BMW320
print(" verification : The instance created by the subclass also belongs to the parent class ")
print(isinstance(BENZ600, Car))
print(isinstance(BMW320, Car))

print(" verification : The instance created by the parent class does not belong to the subclass ")
print(isinstance(BENZ600, BMW))

print(" verification : All instances created by the class belong to the root class ")
print(isinstance(BENZ600, object))
print(isinstance(BMW320, object))

From the running results and combined with the code ：
BENZ600 This instance belongs to both Car class , Also belong to Object class .
in other words ,BENZ600 Inherit Car class , Also inherited Object class , But don't inherit BMW class ;

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Class inheritance

When creating a class , You don't have to start from scratch every time , Suppose that there are some common properties and methods between the new class we want to create and the class we have already created , We can inherit from an existing class , The new class is called Subclass , The inherited class is called Parent class .

inheritance , The subclass will get all the properties and methods of the parent class , And subclasses can also define their own properties and methods .

Grammar rules of subclasses ：class New class name ( Parent class name )

Class inheritance , The subclass belongs to the parent class ; The instance created by the subclass also belongs to the parent class .

#  Statement  super()  A function is a method used to call a parent class 

class Penguin(Bird):
    def __init__(self, n, c, s):
        super().__init__(n, c, s)

        self.swimming_distance = 100

    def get_swimming_distance(self):
        print(f" Penguins can swim {
      self.swimming_distance} rice ")


my_bird = Penguin(' penguin ', ' Black and white ', ' Big ')
my_bird.get_description()

my_bird.get_swimming_distance()

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Inheritance also includes multi-level inheritance and multi inheritance

Multiple inheritance

What is? Multiple inheritance ？
Subclasses can call the properties and methods of the parent class , You can also call the properties and methods of the parent class . This is it. Multiple inheritance .

#  Stars 
class Star:
    glasses = " sunglasses "


#  Musicians inherited stars 
class Musician(Star):
    loveMusic = True


# Rapper Inherited musicians 
class Rapper(Musician):
    pass


csunYuk = Rapper()
print(csunYuk.glasses)
print(csunYuk.loveMusic)

[^1] example csunYuk It's a class Rapper establish , It can call the parent class Musician Properties of , You can also call the parent class of the parent class Star Properties of .

multiple inheritance

What is? multiple inheritance Well ？

A class can inherit multiple classes , Grammar is class Z(X,Y)

#  Musician 
class Musician():
    loveMusic = True
    
    def intr(self):
        print(" I like music ")
        print(" I come from the music industry ")
        
        
#  Speaker 
class Orator():
    speak = " Speak fluently "
    
    def intr(self):
        print(" I like speaking ")
        print(" I come from the speech industry ")
        
        
# Rapper Inherited musicians and speakers 
class Rapper(Musician, Orator):
    pass


csunYuk = Rapper()
print(csunYuk.loveMusic)
print(csunYuk.speak)
csunYuk.intr()

csunYuk Inherited Parent class Musician Of attribute loveMusic, Also inherited Parent class Orator Of attribute speak;
When both parent classes have intr() Class method , It will inherit the parent class on the left first , That 's the parent class Musician Methods ;

In multiple inheritance , Subclasses inherit properties and methods from multiple parent classes , But it takes precedence over the properties and methods of the parent class on the left

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Class customization

Subclasses can be customized on the basis of inheriting the parent class : You can create new attributes 、 The new method ; You can also change the inherited properties or methods .

On the basis of inheriting the parent class , It can be changed

#  Musician 
class Musician():
    loveMusic = True

    def intr(self):
        print(" I like music ")
        print(" I come from the music industry ")

    def sing(self):
        print(" I'm singing ")


# Rapper Inheritor 
class Rapper(Musician):     #  Class inheritance 
    def sing(self):         #  Class customization , Change method 
        print(" I sing in the form of speaking ")


csunYuk = Rapper()
csunYuk.sing()

# csunYuk It's through  Rapper Instantiated object , Rapper Class inheritance Musician class ,
#  Nature will inherit Musician Class method sing;

#  however Rapper Class will sing Method to rewrite , cause csunYuk.sing() At the end of the run , 
#  The result of printing is “ I sing in the form of speaking ”

————————————————————————————————————————————

pandas Practice every day ：

EXCEL Documents are prepared in advance ：

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Guide library 、 Reading documents

# -*- coding = utf-8 -*-
# @Time : 2022/7/23 20:38
# @Author : lxw_pro
# @File : pandas-6  practice .py
# @Software : PyCharm

import pandas as pd
df = pd.read_excel('text5.xlsx')

26、 Look at the index 、 Data types and memory information

df.info()

The program runs as follows ：

<class 'pandas.core.frame.DataFrame'>
RangeIndex: 8 entries, 0 to 7
Data columns (total 7 columns):
 # Column Non-Null Count Dtype 
---  ------        --------------  -----         
 0   Unnamed: 0    8 non-null      int64         
 1   Unnamed: 0.1  8 non-null      object        
 2   project       8 non-null      object        
 3   popularity    8 non-null      int64         
 4   test_time     8 non-null      datetime64[ns]
 5   date          8 non-null      datetime64[ns]
 6   time          8 non-null      object        
dtypes: datetime64[ns](2), int64(2), object(3)
memory usage: 576.0+ bytes

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27、 View summary statistics for numeric Columns

print('describe', df.loc[:, ['popularity']].describe())

The program runs as follows ：

describe        popularity
count    8.000000
mean   125.000000
std     28.963031
min     84.000000
25%     94.250000
50%    143.000000
75%    146.500000
max    149.000000

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28、 Add a new column based on popularity Divide the data into n Group

fz = [0, 80, 120, 150]
fz_names = [' good I', ' good II', ' good ']
df['scores'] = pd.cut(df['popularity'], fz, labels=fz_names)
print(df)

The program runs as follows ：

   Unnamed: 0 Unnamed: 0.1  project  ...       date      time scores
0           0     00:00:00   Python  ... 2022-06-20  18:30:20    good II
1           1            1     Java  ... 2022-06-18  19:40:20    good II
2           2            2        C  ... 2022-06-08  13:33:20      good 
3           3            3    MySQL  ... 2021-12-23  11:26:20      good 
4           4            4    Linux  ... 2021-12-20  18:20:20    good II
5           5            5     Math  ... 2022-07-20  16:30:20      good 
6           6            6  English  ... 2022-06-23  15:30:20      good 
7           7            7   Python  ... 2022-07-19  09:30:20      good 
[8 rows x 8 columns]

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29、 according to popularity Columns sort data in descending order

print(df.sort_values('popularity', ascending=False))

The program runs as follows ：

   Unnamed: 0 Unnamed: 0.1  project  ...       date      time scores
7           7            7   Python  ... 2022-07-19  09:30:20      good 
5           5            5     Math  ... 2022-07-20  16:30:20      good 
6           6            6  English  ... 2022-06-23  15:30:20      good 
2           2            2        C  ... 2022-06-08  13:33:20      good 
3           3            3    MySQL  ... 2021-12-23  11:26:20      good 
0           0     00:00:00   Python  ... 2022-06-20  18:30:20    good II
1           1            1     Java  ... 2022-06-18  19:40:20    good II
4           4            4    Linux  ... 2021-12-20  18:20:20    good II
[8 rows x 8 columns]

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30、 Take out No 6 Row data

print(df.loc[5])

The program runs as follows ：

Unnamed: 0                        5
Unnamed: 0.1                      5
project                        Math
popularity                      148
test_time       2022-07-20 16:30:20
date            2022-07-20 00:00:00
time                       16:30:20
scores                            good 
Name: 5, dtype: object

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A word a day ：

In life , The important thing is not victory , But struggle , Something indispensable to life , Not to win , But once fought without regret .

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Ongoing update …

give the thumbs-up , Your recognition is my creation power ！
Collection , Your favor is my effort Direction ！
Comment on , Your opinion is my progress Wealth ！
Focus on , Your love is my lasting insist ！

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