Python List copy()

The copy() method returns a shallow copy of the list. Here's a quick example:

models = ['Claude', 'ChatGPT', 'Gemini']

ai_models = models.copy()
print(ai_models)

# Output: ['Claude', 'ChatGPT', 'Gemini']

It is important to note that we can't just use = to copy a list.

For example, the statement ai_models = models makes both ai_models and models point to the same object (rather than creating a copy). Therefore, changes made to one list also affects the other.

copy() Syntax

The syntax of copy() is:

new_list = my_list.copy()

Arguments

copy() doesn't take any arguments.

Return Value

copy() returns a shallow copy of the list.

Example: Reference Assignment

As mentioned above, using = without copy() makes a variable reference the same list without creating a copy. Therefore, if you make changes to one list, the changes will also be reflected in the other.

models = ['Claude', 'ChatGPT', 'Gemini']

ai_models = models

# Removing the last item
models.pop()

print(f'Models: {models}')
print(f'AI Models: {ai_models}')

Output

Models: ['Claude', 'ChatGPT']
AI Models: ['Claude', 'ChatGPT']

As we can see, when models is changed, ai_models is also modified because we haven't used copy().

Example: Copy Using Slicing

Instead of using copy(), we can also use list slicing to copy a list.

models = ['Claude', 'ChatGPT']

# Copy using slicing
ai_models = models[:]

models.append("Gemini")

print(f'Models: {models}')
print(f'AI Models: {ai_models}')

Output

Models: ['Claude', 'ChatGPT', 'Gemini']
AI Models: ['Claude', 'ChatGPT']

You can read more about Python slicing here.