Python Copy Module

Python Copy Module

python copy module is used for copying elements of a list, object, array etc.

Python copy module is used to creating shallow as well as deep copies.

copy module is a built-in package for python 3.x version.

The copy module basically have two functions

1. copy( )
2. deepcopy( )

we will discuss each one by one but first understand the usage of copy module.

Lets take a example code and copy a list with out copy module functions.

       			 
#Dynamic Coding
#copy module
# working without copy module.

a = [[1, 2, 3],[4,5,6]]
b = a


print(a)
print(b)

a[1][1] = 23
b[0][0] = 98


print('List a ',a)
print()
print('List a ',b)
 

  Output  

[[1, 2, 3], [4, 5, 6]]
[[1, 2, 3], [4, 5, 6]]

List a [[98, 2, 3], [4, 23, 6]]

List a [[98, 2, 3], [4, 23, 6]]

This code represents an example of shallow copy.

As you can see in the output the change on list  a at index 1 is also reflected on on list b and same the change on list b index 0 is visible on list a & because of this we use copy module function / method because when we modify one list the another list which is the copy of first list will not affected if we are using deepcopy( ) method of copy module.

Lest move to our topic .

1. copy.copy( )  :

This method creates shallow copy of a list or array etc.

shallow copy means both list will point to same object.

code to illustrate:

       			 
#Dynamic Coding
#copy module

import copy

a = [[1, 2, 3],[4,5,6]]

b = copy.copy(a)

print(a)
print(b)

a[1][1] = 23
b[0][0] = 98


print('List a ',a)
print()
print('List a ',b)
 

  Output  

[[1, 2, 3], [4, 5, 6]]
[[1, 2, 3], [4, 5, 6]]

List a [[98, 2, 3], [4, 23, 6]]

List a [[98, 2, 3], [4, 23, 6]]

Note : in our code we use a 2 dimensional list but if we use a 1 D list then the copy( ) function will work same like deepcopy( ) function means the modification of one will not affect other.

---

2. copy.deepcopy( )  :

The deepcopy( ) method returns a deepcopy of the list passed to it.

The deepcopy( ) creates a separate list with no relation with original one.

it basically means the change on list 1 will not affect list 2 which is the copy of list 1 and viceversa.

in deepcopy both list will point on different object.

code to illustrate:

       			 
#Dynamic Coding 
# copy module
# deep copy 
import copy

a = [1, 2, 3]


b = copy.deepcopy(a)

print(a)
print(b)

a[1] = 23
b[0]= 98

print('List a ',a)
print()
print('List a ',b)
 

  Output  

[1, 2, 3]
[1, 2, 3]

List a [1, 23, 3]

List a [98, 2, 3]

As you can see in the output we change data at both list index but modification of one list is not reflected to Another list.

---

Thanks for Visiting.

if you face any error or doubt let us know in comment section,. we will reply back you as soon as possible.