Python add list to list

In this post, you will learn how to add a list to a list in the Python programming language.

A list is an arranged collection of elements. It can contain a list of various types of data objects with a comma separated and enclosed within a square bracket. It is mutable, which means we can change the order of elements in a list. In the development process, we may come to a situation in which we need to add a list to the existing list. There are several ways to join two or more lists in Python, like append(), extend(), insert() methods. Here, we have mentioned four ways to add a list to a list -

Python add list to list using add (+) operator

To add multiple lists, we can use the concatenate (+) operator. This will create a new list and the original lists will stay unaltered. Here is the basic example-

list1 = [30, 27, 26]
list2 = [11, 43, 25]

list = list1 + list2
print(list)

[30, 27, 26, 11, 43, 25]

Python add list to list using append() method

The append() method appends an element to the end of the list. The syntax of the append() is-

list.append(item)

This method accepts a single argument. In the given example, we have appended one list to the other list-

# first list
item1 = ['book', 'pen', 'copy']

# second list
item2 = ['bag', 'colors', 'pencil']

# appending item2 list to the item1 list
item1.append(item2)

print('Updated list: ', item1)

Updated list:  ['book', 'pen', 'copy', ['bag', 'colors', 'pencil']]

Python add list to list using insert() method

The insert() function adds an element at the specified index of the list. It's valuable to add an element at the specified position on the list. Here is the syntax-

list.insert(index, element)

Here, the index is the index at which the element has to be inserted, element is the element to be inserted in the list. It is of any data type (string, number, object etc). Both index and element are required parameters.

x = list(range(5))
print(x)

x.insert(0, 100)
print(x)

x.insert(1, 101)
print(x)

[0, 1, 2, 3, 4]
[100, 0, 1, 2, 3, 4]
[100, 101, 0, 1, 2, 3, 4]

Python add list to list using extend() method

In Python, the extend() method append iterable elements to the list. It is helpful to attach elements from an iterable to the end of the list. Here is the syntax-

list.extend(iterable)

This method accepts only one parameter which is required. The iterable can be any list, tuple, object, etc. Here is the simple example.

fruits = ['pineapple', 'cherry', 'mangoes']

citrus = ['orange', 'lemon', 'grapefruits']

fruits.extend(citrus)

print(fruits)

['pineapple', 'cherry', 'mangoes', 'orange', 'lemon', 'grapefruits']

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