Python copy set by value

copy a list of set by values in python

It creates a completely different set of memory spaces and is not a shallow copy that simply points to the same memory space.

You are only creating a shallow copy of store ; the referenced mutable sets are not copied.

You’d have to copy each set too:

items = [set(s) for s in store] 

import copy items = deepcopy(store) 

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Python Set copy() Method

Python set copy() method creates a shallow copy of the set and returns the copied set. This method does not take any parameters and returns a new set object. A shallow copy means that a new set is created with the same elements as the original set, but the elements themselves are not copied, instead, the new set contains references to the same objects as the original set. So any changes to the copied set won’t reflect on the original set.

In this article, I will explain the Python set copy() method syntax, parameters, and usage of how to copy all the elements from a given set with examples.

1. Quick Examples of Set copy() Method

If you are in a hurry, below are some quick examples of the set copy() method.

 copied_set = myset.copy() # Example 2: Copying a set # Using = operator myset = copied_set = myset # Example 3: Using set() constructor copied_set = set(myset) 

2. Python Set copy() Method

set.copy() method is used to create a shallow copy of a set. It returns a new set object with the same elements as the original set. This method does not allow any arguments and returns a new set object that contains references to the same objects as the original set.

2.1 Syntax of Set copy() Method

Following is the syntax of the set copy() method.

2.2 Parameter of copy()

The set copy() method does not take any parameter.

2.3 Return Value

It returns a new set object that contains the same elements as the original set and does not modify the original set itself.

3. Copying a Set using the copy() Method

You can copy a set using the copy() method in Python. First, define a set called myset with four elements. Then, you use the copy() method to create a copy of the set and assign it to the variable copied_set . Finally, you print the original set and the copied set to verify the result.

Note: If you modify the copied set changes, won’t be reflected in the original set.

 print("Original set: ", myset) # Copying a set # Using the copy() method copied_set = myset.copy() print("Copied set: ", copied_set) 

4. Add Element to the Set After using copy()

The copy() method creates a shallow copy of a set in Python, which means it creates a new set object with the same elements as the original set. However, after using copy() , you can still modify the original set or the copied set independently. If you want to add items to the set after using copy() , you can do so by directly modifying either the original set or the copied set.

5. Other Ways to Copy Set Elements

Besides the copy() method, you can also copy the elements using = assignment operator and set() constructor. Let’s see these with examples.

5.1 Using the set() Constructor

You can use the set() constructor to copy the elements which is similar to the copy() method. For instance, the set() constructor or the copy() method creates a new set object with the same elements as the original set, allowing you to modify one set without affecting the other.

 print("Original set: ", myset) # Using set() constructor copied_set = set(myset) # Add an element to set copied_set.add("Java") print("Copied set: ", copied_set) # Output: # Original set: <'C++', 'Python', 'Hadoop', 'Spark'># Copied set:

5.2 Copying a Set Using = Operator

Unlink the above two methods the behavior of the = assignment operator is different. Use the = assignment operator to assign a set to a new variable, with this, you are not creating a copy of the set. Instead, both the original set and the new variable will refer to the same set object. Any changes made to the set through one variable will be reflected in the other variable as well.

 # Copy set using = copied_set = myset # Copying a set # Using = operator copied_set.add("Java") print("Original set: ", myset) print("Copied set: ", copied_set) 

6. Conclusion

In this article, I have explained the Python set copy() method and using its syntax, parameters learned how to copy all the elements from a given set with examples. This method does not take any parameters and returns a new set object.

The copy() performs a shallow copy meaning a new set is created with the same elements as the original set, but the elements themselves are not copied. Instead, the new set contains references to the same objects as the original set. So any changes to the copied set won’t reflect on the original set.

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Python Set copy() Method with examples

The copy() method in Python returns a copy of the Set. We can copy a set to another set using the = operator, however copying a set using = operator means that when we change the new set the copied set will also be changed, if you do not want this behaviour then use the copy() method instead of = operator. We will discuss these with the help of examples.

Python Set copy() method Syntax

Parameters: None. This method doesn’t take any parameter.
Return value: Returns the copy of the given set

Copying a Set using = operator

In the following example we are copying a set to another set using = operator. The problem with this method is that if any of the set (old or new) is modified, the changes will reflect in both the sets. Here we have a set names and we copied this set to a new set names2 .

After the copy using = operator, we have made changes in both the sets (added an element in new set and removed an element from old set), both the changes reflect in both the sets as shown in the following example. If you do not want this kind of behaviour and only want the set where you are making changes to be changed then use copy() method, which is discussed in the next section.

# A Set of names names = names2 = names # adding a new element in the new set names2.add("Glenn") # removing an element from the old set names.remove("Negan") print("Old Set is:", names) print("New Set is:", names2)

Output:

Python Set copy() method example

Lets take the same example that we have seen above, however here we are copying the set using the copy() method. As you can see in the output that only the change that we have made to the old and new set reflect and both doesn’t share the same copy of the set as shown in the above example.

# A Set of names names = # copying using the copy() method names2 = names.copy() # adding "Glenn" to the new set names2.add("Glenn") # removing "Negan" from the old set names.remove("Negan") # displaying both the sets print("Old Set is:", names) print("New Set is:", names2)

Output:

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About the Author

I have 15 years of experience in the IT industry, working with renowned multinational corporations. Additionally, I have dedicated over a decade to teaching, allowing me to refine my skills in delivering information in a simple and easily understandable manner.

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