Copy Lists

 

What You'll Learn: In this tutorial, you'll discover different ways to copy a list in Python. Copying lists allows you to create a separate list with the same items, without linking them together.

Why Not Just Use Assignment?

You can't simply copy a list by typing list2 = list1. This will only create a reference to list1, meaning changes to list1 will also affect list2.

Method 1: Use the copy() Method

You can use the built-in copy() method to create a copy of a list.

Example Code:

python
thislist = ["apple", "banana", "cherry"]
mylist = thislist.copy()
print(mylist)

Output: ['apple', 'banana', 'cherry']
 

What's Happening Here?

  • thislist.copy() creates a new list mylist that is a copy of thislist.

Method 2: Use the list() Method

Another way to make a copy is to use the built-in list() method.

Example Code:

python
thislist = ["apple", "banana", "cherry"]
mylist = list(thislist)
print(mylist)

Output: ['apple', 'banana', 'cherry']
 

What's Happening Here?

  • list(thislist) creates a new list mylist that is a copy of thislist.

Method 3: Use the Slice Operator

You can also make a copy of a list by using the slice operator [:].

Example Code:

python
thislist = ["apple", "banana", "cherry"]
mylist = thislist[:]
print(mylist)

Output: ['apple', 'banana', 'cherry']
 

What's Happening Here?

  • thislist[:] creates a new list mylist that is a copy of thislist.

Try It Yourself: Fun Exercises

  1. Copy Your Favorite Movies List:
    • Create a list of your favorite movies.
    • Use the copy() method to create a duplicate list.
  2. Duplicate Your Snack List:
    • Make a list of snacks.
    • Use the list() method to copy the list.
  3. Clone Your Book List:
    • Write a list of books you want to read.
    • Use the slice operator [:] to clone the list.

Summary:

In this Python tutorial, we learned different ways to copy a list using the copy() method, list() method, and the slice operator [:]. Copying lists allows you to create separate lists with the same items, without affecting each other. Keep experimenting and have fun with lists in Python!