Python Dictionary copy()

original_marks = {'Physics':67, 'Maths':87}

copied_marks = original_marks.copy()


print('Original Marks:', original_marks)
print('Copied Marks:', copied_marks)

# Output: Original Marks: {'Physics': 67, 'Maths': 87}
#         Copied Marks: {'Physics': 67, 'Maths': 87}

Syntax of Dictionary copy()

The syntax of copy() is:

dict.copy()

copy() Arguments

The copy() method doesn't take any arguments.

copy() Return Value

This method returns a shallow copy of the dictionary. It doesn't modify the original dictionary.

Example 1: How copy works for dictionaries?

original = {1:'one', 2:'two'}
new = original.copy()


print('Orignal: ', original)
print('New: ', new)

Output

Orignal:  {1: 'one', 2: 'two'}
New:  {1: 'one', 2: 'two'}

Dictionary copy() Method Vs = Operator

When the copy() method is used, a new dictionary is created which is filled with a copy of the references from the original dictionary.

When the = operator is used, a new reference to the original dictionary is created.

Example 2: Using = Operator to Copy Dictionaries

original = {1:'one', 2:'two'}
new = original


# removing all elements from the list
new.clear()

print('new: ', new)
print('original: ', original)

Output

new:  {}
original:  {}

Here, when the new dictionary is cleared, the original dictionary is also cleared.

Example 3: Using copy() to Copy Dictionaries

original = {1:'one', 2:'two'}
new = original.copy()


# removing all elements from the list
new.clear()

print('new: ', new)
print('original: ', original)

Output

new:  {}
original:  {1: 'one', 2: 'two'}

Here, when the new dictionary is cleared, the original dictionary remains unchanged.