Python Set copy()

February 2, 2021

copy() in Python Sets

The copy() method returns the copy of the set in python.

When we use “=” sign to copy the set, if we modify the copied set then the changes are also reflected back in the original set. So here we have to create a shallow copy of the set such that when we modify something in the copied set, changes are not reflected back in the original set.

Syntax :

set2=set1.copy()

Return Type :

The copy() method returns a shallow copy of the set in python.

#copy() in python set

set1 = {1, 2, 3, 4, 5 }
print(“Set 1 : “,set1)

#all the values of set1 is copied to the set2
set2=set1.copy()
print(“Set 2 : “,set2)

#modifying set2
set2.add(10)
print(“After adding new element in set2”)
#changes is reflected in only set2 not in set1
print(“Set 1 : “,set1)
print(“Set 2 : “,set2)

Output :

Set 1 :  {1, 2, 3, 4, 5}
Set 2 :  {1, 2, 3, 4, 5}

After adding new element in set2
Set 1 :  {1, 2, 3, 4, 5}
Set 2 :  {1, 2, 3, 4, 5, 10}

In the above code the modification in copied set is only reflected in copied set.

See the below example to understand the difference between copy() and “=”.

# “=” in python set

set1 = {1, 2, 3, 4, 5 }
print(“Set 1 : “,set1)

#all the values of set1 is copied to the set2
set2 = set1
print(“Set 2 : “,set2)

#modifying set2
set2.add(10)
print(“After adding new element in set2”)

#changes is reflected in both set2 and set1
print(“Set 1 : “,set1)
print(“Set 2 : “,set2)

Output :

Set 1 :  {1, 2, 3, 4, 5}
Set 2 :  {1, 2, 3, 4, 5}

After adding new element in set2
Set 1 :  {1, 2, 3, 4, 5, 10}
Set 2 :  {1, 2, 3, 4, 5, 10}