# Append to a list based on occurrence in python

When working with lists in Python, it is often necessary to append elements to the list based on certain conditions or occurrences. In this article, we will explore three different ways to solve the problem of appending elements to a list based on occurrence in Python.

## Option 1: Using a for loop

One way to solve this problem is by using a for loop to iterate over the elements and append them to a new list based on a specific condition. Here is an example:

``````input_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
output_list = []

for element in input_list:
if element % 2 == 0:
output_list.append(element)

print(output_list)``````

In this example, we have an input list containing numbers from 1 to 10. We iterate over each element in the input list and check if it is divisible by 2. If it is, we append it to the output list. The output list will then contain all the even numbers from the input list.

## Option 2: Using list comprehension

List comprehension is a concise way to create lists in Python. It can also be used to solve this problem. Here is an example:

``````input_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
output_list = [element for element in input_list if element % 2 == 0]

print(output_list)``````

In this example, we use list comprehension to create a new list called output_list. We iterate over each element in the input list and check if it is divisible by 2. If it is, we include it in the output list. The output list will then contain all the even numbers from the input list, just like in the previous example.

## Option 3: Using the filter() function

The filter() function in Python can be used to filter elements from a list based on a specific condition. Here is an example:

``````input_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
output_list = list(filter(lambda x: x % 2 == 0, input_list))

print(output_list)``````

In this example, we use the filter() function along with a lambda function to create a new list called output_list. The lambda function checks if each element in the input list is divisible by 2. If it is, the element is included in the output list. The output list will then contain all the even numbers from the input list.

After exploring these three different options, it is clear that using list comprehension is the most concise and readable solution. It allows us to create a new list based on a condition in a single line of code. Therefore, option 2 is the better choice for solving the problem of appending elements to a list based on occurrence in Python.

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### 7 Responses

1. Ricky says:

I personally think option 2 is the way to go, but hey, to each their own! #PythonMadness

2. Lia Frank says:

Option 2 all the way! List comprehension is like magic, makes code look clean and fancy ✨🔥

3. Maliyah says:

Option 3 with filter() is like finding a hidden treasure in the Python jungle! 🌳🐍🔍

4. Cooper Reid says:

Option 2 is the way to go! List comprehension for the win! 🙌🏼

1. Charlie says:

Sorry, but I have to disagree. Option 1 is much more efficient and readable. List comprehension might look cool, but it can easily become a tangled mess. Stick with what works and keep it simple.

5. Emerson says:

Option 2 using list comprehension is the way to go, its shorter and sweeter! 🙌🏼

6. Emerson says:

Option 2 is like adding sprinkles to ice cream – its quick, easy, and adds a nice touch! 🍦🌈