I. Deep and Shallow Copies

Shallow copy: Copy the first layer (top-level object), or parent object

Deep copy: Copy all objects, top-level objects and their nested objects, or parent objects and their children

# Copy one copy at a time (but not because of small datapools)
v1 = 'alex'
import copy
v2 = copy.copy(v1)
print(id(v1),id(v2))     #Same address    

Exercise 1
impot copy
v1 = [1,2,3]
v2 = copy.copy(v1)   #shallow copy
print(v1 == v2)  # True
print(v1 is v2)  # False
print(v1[0] is v2[0])  # True

Exercise 2

 import copy
 v1 = [1,2,3,{"name":'Wu Po Qi',"numbers":[7,77,88]},4,5]
 v2 = copy.copy(v1)
 print(v1 is v2)       #False
 print(v1[0] is v2[0])  #True
 print(v1[3] is v2[3])  #True
 print(v1[3]['name'] is v2[3]['name'])    #True
 print(v1[3]['numbers'] is v2[3]['numbers'])   #True
 print(v1[3]['numbers'][1] is v2[3]['numbers'][1])   #True

Exercise 3
import copy
v1 = [1,2,3,{'k1':123,'k2':456}]
v2 = copy.deepcopy(v1)
print(v1 == v2) # True
print(v1 is v2) # False
print(v1[0] is v2[0]) # True
print(v1[3] == v2[3]) # True
print(v1[3] is v2[3]) # False

Exercise four
 Import import import copy V1 = import copy V1 = [1,2,3, {name":'Wupei Qi', {number": [7,77,88]]], 4,5] V2 = copy. deepcopy (v1) print (v1 is v2) # False print (v1 [0] is V2 [0]] # True print (v1 [0]]] #True print (v1 [v1 [3] is V2 [3] is V2 [3]] #False print (v1 [v1 [3]]['v1 [3]] ['v1]]['name] \fonfonfonfonfonfonfonfonfonfonfonfonfonfonfonfonfonfon3]['numbers'] # False print (v1 [3]['numbers'] [1] is V2 [3]['numbers'] [1]) # True

II. File Operation

1. Read: r (read): Can only read but not write, if the file does not exist, it will report an error.

#Open file:
    object = open('some txt file',mode = 'r',encoding = 'utf-8')

#Read content:
    content = object.read()
    print(content)

#Close content:
    object.close()

2. Write: w (write): Write but not read (empty the file first), create a new file if it does not exist

#Open file:
    object = open('Certain txt Documents or files to be created',mode = 'w',encoding = 'utf-8')

#Writing content:
    object.write('xxx')

#Close file:
    object.close()

3. Added; a (append): Added only, unreadable, new if nonexistent

#Open file:
    object = open ('Certain txt Documents or files to be created',mode = 'a',encoding = 'utf-8')

#Writing content:
    object.append()

#Close file
    object.close()

3. Documents are readable and writable:

1. Readable and Writable

read
#Write: Write from the current cursor position, depending on the cursor position (other text may be overwritten)

file_object = open('Certain txt file',mode='r+',encoding='utf-8')
file_object.seek(2) # Adjust the position of the cursor(Adjust according to bytes)

#Read content:
content = file_object.read()
print(content)
file_object.write('xxx')

#Close file:
file_object.close()

2. Readable and Writable

object = open ('Certain txt file',mode = 'w+',encoding = 'utf-8')
data = object.read()
print(data)

object.write('xxx')
object.seek(0)
data = object.read()
print(data)

file_object.close()

4. Read and write operations

1. reading:

file_object = open('Certain txt file',mode='r',encoding='utf-8')
# Read all the contents of the file into memory
    con = file_object.read()

#Read back two characters of the file from the current cursor position
    con = file_object.read(2)

# Read all the contents of the file into memory and divide them into lists according to each line.
    data_list = file_object.readlines()

# If you read a particularly large file later (**********)
    for line in file_object: 
         line = line.strip()  # strip : Remove line break(\n)
         print(line)     #Read line by line

2. write:

file_object = open('log.txt',mode='w',encoding='utf-8')
file_object.write('asdfadsfasdf\n')
file_object.write('asdfasdfasdfsadf')
file_object.close()

Five. Practice:

1. Please link the elements in user according to _link and write them to the file'a1.txt'.

    user = ['alex','eric']
    data = '_'.join(user)
    object = open('a1.txt',mode = 'w',encoding = 'utf-8')
    object.write(data)
    object.close()

2. Please link the elements in user according to | and write to the file'a2.txt'.

    user = [
    {'name':'alex','pwd':'123'},   
    {'name':'eric','pwd':'olbody'},]
    object = open('a2.txt',mode = 'w',encoding = 'utf-8')
    for item in user:
        line = '%s|%s\n' %(item['name'],item['pwd'])
        object.write(line)
     object.close()

3. Please read out the files in a2. (2)txt and add them to a list ['alex|123','eric|olbody']

Method 1:
    list = []
    objecct = open('a2.txt',mode = 'r',encoding = 'utf-8')
    for line in object:
       line = line.strip()
       list.append(line)
     print(list)
    
 //Method two:
      file_obj = open('a2.txt',mode='r',encoding='utf-8')
    content = file_obj.read()
    file_obj.close()
    content = content.strip() #Remove the last newline
    data_list = content.split('\n') #Cut according to the line change in the middle
    print(data_list)