How To Append to a List in Python with Examples

In Python, lists are one of the most often used data types. They include a variety of components such as strings, integers, dictionaries, and so on. The Python append method is used to attach a new member to the end of a list.

Python List append

When dealing with python lists, the append() method adds just one iterable or item to the rear part of an original list. It doesn’t return or generate a new list of items, but it does add the item to the end of the existing one.

The append() function accepts only one parameter, which might be either an item or an iterable. The append() function returns a result that modifies the original list rather than producing a new one.

The fundamental syntax is as follows:


To append an object to the rear end of a list, use the append() function.

Python List append

Add a list to a list, for example:

Append to a List in Python examples

The output will be:

Python List append()

In Python, how do you append many items to a list at the same time?

The append() method in Python 3 adds a single item to an existing list. Only one item may be added at a time using the append() function. You’ll want to utilize the extend() function if you wish to add numerous components at once.

The following is the syntax for the extend() method:

append many items to a list at the same time

The extend method accepts a list of items as input and adds each of them as a distinct item to an existing list.

The extend method is demonstrated in the following code:

append several items to a list

We have a list named nations in this example, which contains three countries. We used the extend function to add three additional nations to the list all at once.

We may send another list to the extend() method in Python since it accepts a list as its single parameter, as seen in the following example:

It’s worth noting that the extend method appends each additional item to the list’s end.

Append Vs Extend Method in Python

1Only one element is added to the list.Adds numerous elements to the list, i.e. more than once.
2The length grows by one.The number of components added raises the length by n.
3Has a constant time complexity of O (1).O(n) is the time complexity, where n is the number of items.

How to Append Elements to a String in Python Several Times

Should you need to append to a string consistently in Python, change it to a list, append your items to that list, then merge the list back into a string after you’ve finished.  

Consider the following scenario: you’re seeking lines that start with “ERROR:” in a big log file. All of those lines should be saved as a string and written to a new file.

Your initial instinct might be to do it this way:

Append Elements to a String in Python Several Times

However, because Python strings are immutable, that method necessitates the creation of a new memory allocation each time the string is modified.

Instead, you should carry out the following actions:

  1. Open the log file and enter the following information into a list (e.g., log):

2. Make a new empty list (for example, new log):

3. Append each matching line to the new log list by looping through the log list looking for matches:

4. Write to the new log file by joining the new log on an empty string:

You won’t notice much of a difference if you’re only making a few changes to the string, but if you’re making thousands, this way is substantially more resourceful.

In python lists, what is the difference between append and insert?

In a Python list, the difference between append and insert is that append methods can only be used to add new items to the list, but insert methods may be used to add as well as alter already occupied positions.

Also, the append function accepts one parameter (which you must put into the list), but the insert method requires two elements (the first being the element’s location and the second being the element itself). Here are some examples of how to use both methods:

Using append

append vs insert python

Using insert

You can put an element in any location, but it will be stored right after the last one. This reasoning is based on the reality that lists organize data.  

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