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Why comprehensions are the most preferred way to construct new sequences in Python

How to use list and loop comprehensions in Python to perform complex tasks

Comprehensions homework help

Python is a high-level programming language that is particularly famous for allowing the programmer to write elegant code. The language is easy to learn and write because, in most cases, it’s like plain English language. This is one of the programming languages that ushers you into the programming world before you can think of using other languages such as C or C++. One of the most distinctive features of python is comprehension, which adept programmers use to simplify the length of code to a single line of code in the list, set, and dictionary creations.

This article will provide you with a basic understanding of the power of Pythonic list comprehensions and how to apply comprehensions comfortably. This would also help if you want to pay for the comprehension homework by being informed about the inner details of the topic.

List comprehension

Comprehensions provide an alternative way of creating lists in python. There are other means of creating lists that most are accustomed to. To better understand what comprehensions are and why you should be using them, it’s good to look at all the methods of list creation. Here are some of the methods that can be used to create a list in python.

Using for Loops

When we talk of loops, the most common type is ‘for loops.’ There are other loops, such as the ‘while loop.’ ‘For loop’ can be put to varied use, but one of them is the creation of list elements. Are you wondering how this can be done?

There is a sequence of steps that you have to follow when creating lists from this loop. These are:-

1. Instantiation of an empty list.

2. Secondly, use for a list to loop over an iterable

3. For each element, add it to the lists. This is normally done using the append function

Let’s clarify the above points with python code. If you want to create a list of the first five numbers, you will do it following the above steps.

K= []

For I in range (5):

k.append (i)

The map () method

The map () method is a functional programming approach that can create lists. For this method, you pass a function and an iterable. This can be shown in its syntax that is given below:-  

Map (sequence, callback)

The sequence is iterable, and the callback is the function that accepts an argument. The results are the output derived from running the function over each element of literals.

List comprehension

This is the third way in our group that can be used to create a list. It’s much like an alternative to the first method of creating function. Only that in this case, the function is created in just a single line. In most cases, you will always use ‘for loops' to create the list. Below is how the above function in the above list can be written:

K = [i for i in range (5)]

See how simplified this method is. Here you avoided creating an empty list and adding the results from the ‘for loop’ to the list. Here everything is straightforward. Simply define the list and its contents.

Here are some of the basic features of a list comprehension that should guide you when creating one.

1. Expression. This is a valid expression like getting the square root of the elements. In the above case, we have not included an expression as it was the most basic list that you can create, but there are instances that you want to create a list of the squares of the first hundred numbers. This is where it becomes clear.

2. Member. This is the element of the iterable. In our case, the member value is i. you can use any value besides i.

3. Iterable. This is the sequence over which the elements can be looped over. In our case, the iterable is range (5).

Due to the flexibility, list comprehensions can also work well where maps are used.

Warning on the usage of list comprehension. 

List comprehension is an elegant way of writing your code, but there are instances where it’s better to use the ‘for loops’ than the list comprehension. An example is where you are writing a long code. Using list comprehensions now and then would impact the readability of the code. Therefore, you should carefully analyze when to use list comprehension.

If you have any queries on list comprehensions, please contact our online list comprehension experts for instant help.

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