Building a list inside a list in python

When working with Python, there may be situations where you need to build a list inside another list. This can be achieved in different ways, depending on your specific requirements and preferences. In this article, we will explore three different approaches to solve this problem.

Option 1: Using List Comprehension

List comprehension is a concise and elegant way to create lists in Python. It allows you to build a list by iterating over an existing iterable and applying a condition or transformation to each element. To build a list inside a list, you can use nested list comprehension.

outer_list = [inner_list for inner_list in range(5)]

In this example, we are creating a list called outer_list by iterating over a range of numbers. Each element in the range is assigned to a new list called inner_list. The result is a list of lists, where each inner list contains a single number.

Option 2: Using Append Method

If you prefer a more traditional approach, you can use the append() method to add elements to a list. To build a list inside a list, you can create an empty outer list and then append inner lists to it.

outer_list = []
for i in range(5):
    inner_list = [i]
    outer_list.append(inner_list)

In this example, we start with an empty list called outer_list. Inside a loop, we create a new list called inner_list with a single element, which is the current value of i. We then append the inner_list to the outer_list. This process is repeated for each iteration of the loop, resulting in a list of lists.

Option 3: Using List Concatenation

Another way to build a list inside a list is by using list concatenation. This involves creating an empty outer list and then concatenating inner lists to it using the + operator.

outer_list = []
for i in range(5):
    inner_list = [i]
    outer_list += [inner_list]

In this example, we start with an empty list called outer_list. Inside a loop, we create a new list called inner_list with a single element, which is the current value of i. We then concatenate the inner_list to the outer_list using the += operator. This process is repeated for each iteration of the loop, resulting in a list of lists.

After exploring these three options, it is clear that the best approach depends on the specific requirements of your program. If you prefer a concise and elegant solution, list comprehension is a great choice. However, if you prefer a more traditional approach or need more control over the list-building process, using the append() method or list concatenation may be more suitable. Ultimately, the choice between these options should be based on readability, performance, and personal preference.

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9 Responses

    1. I respectfully disagree. Option 1 offers better readability and maintainability. Simplicity is key, my friend. Lets not complicate things unnecessarily. #KeepItSimple #PythonCodingSquad 🐍👌

    1. Are you kidding? Option 3 is far more efficient and readable than list comprehension. Dont be scared of a little extra work, it pays off in the long run. 🙄

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