Python .copy()

The .copy() method returns a shallow copy of a deque.

Syntax

copied_deque = original_deque.copy()

Parameters:

The .copy() method takes no parameters.

Return value:

Returns a new deque object that is a shallow copy of the original deque.

Example 1: Reference copy using assignment

The example shows that assigning one deque to another with = creates a reference, not a real copy:

from collections import deque

deque1 = deque([1, 2, 3, 4])
deque2 = deque1

print(deque1)
print(deque2)

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The output of this code is:

deque([1, 2, 3, 4])
deque([1, 2, 3, 4])

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However, modifications to deque2 affect deque1 since both refer to the same object.

Example 2: Creating a shallow copy

In this example, a separate deque is created using .copy(), leaving the original unchanged:

from collections import deque

orders = deque(['daisies', 'periwinkle'])
new_orders = orders.copy()

print(new_orders)

# Modify the new deque
new_orders.append('roses')

print(orders)
print(new_orders)

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The output of this code is:

deque(['daisies', 'periwinkle'])
deque(['daisies', 'periwinkle'])
deque(['daisies', 'periwinkle', 'roses'])

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The original orders deque remains unchanged when new_orders is modified.

Codebyte Example

The following example demonstrates the difference between assignment and .copy():

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