DEV Community: Afiz

Find the factorial of given number in Python

Afiz — Mon, 06 Jun 2022 16:43:17 +0000

Method 1: Finding the factorial of a given number using for loop

def factorial(number):
    output = 1
    if number < 2:
        return output
    else:
        for i in range(2, number+1):
            output *= i
    return output

print(factorial(5))

# output: 120

Method 2: Finding the factorial of a given number using recursion

def factorial_recursion(number):
    if number < 2:
        return 1
    return number * factorial_recursion(number -1)def factorial_recursion(number):
    if number < 2:
        return 1
    return number * factorial_recursion(number -1)

print(factorial_recursion(5))

# output: 120

Method 3: Finding the factorial of a given number using the lambda function

factorial_lambda = lambda number: 1 if number  < 2 else  number * factorial_lambda(number -1)

print(factorial_recursion(5))

# output: 120

Thanks for reading this post. Let me know which one is your favorite method.

How to remove duplicates from a list in Python?

Afiz — Thu, 13 Jan 2022 14:12:12 +0000

In this post, we will discuss how to remove duplicates from a list in Python.

There are many ways to delete duplicates from a list, but I find these two methods easy and readable.

Using sets
Using fromkeys method of dict

Please take a look the examples below.

If you like this content, consider following me. Thanks

How to find nth largest/smallest item from a List in Python

Afiz — Tue, 04 Jan 2022 10:36:21 +0000

Do you know you can find n largest/smallest items from a list using heapq python standard library?

Check out this example below:

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How to sort a list in Python

Afiz — Mon, 03 Jan 2022 17:26:40 +0000

In this post we will discuss how to sort list in Python.

There are mainly two ways to sort a list in Python.

sorted function
sort method

1. `sorted` function:

This sort the given list and generate a new list, which means existing list won't be modified.

In [1]: numbers = [23, 42, 12, 121, 45, 9, 8]

In [2]: sorted(numbers)
Out[2]: [8, 9, 12, 23, 42, 45, 121]

In [3]: numbers
Out[3]: [23, 42, 12, 121, 45, 9, 8]

As you can see in the above example Out[3] has the same numbers list.

2. `sort` method:

This method applies the sorting on the list and updates the existing list. This is called in place sorting.

In [4]: numbers.sort()

In [5]: numbers
Out[5]: [8, 9, 12, 23, 42, 45, 121]

Key param:

sorted and sort methods takes an extra parameter called key. Using this key param we can control the sorting.

Example: names = ['Bob', 'Charles', 'James']. Let's say we want to sort the above list of names based on length of the each time.
Solution:

In [7]: sorted(names, key=len)
Out[7]: ['Bob', 'James', 'Charles']

We can pass any function we want to this key. Let me know which method you like in the comments. If you like this content consider following me.

How to create dictionary with two lists in Python

Afiz — Sun, 02 Jan 2022 17:19:44 +0000

In this post, we will discuss how to create a new dictionary out of two lists.
First let's see the input and expected output and then the actual source code of the problem.

input:

keys = ['name', 'age', 'contact']
values = ['Afiz', 30, '9090909090']

expected output:

{'name': 'Afiz', 'age': 30, 'contact': '9090909090'}

There are multiple ways to solve this problem.

Method 1: First let's see the simple way using for loop in Python.

my_dictionary = {}

for i in range(len(keys)):
    my_dictionary[keys[i]] = values[i]

print(my_dictionary)

This solution is okay but not great. Let's check out another method which more pythonic way of doing it.

print(dict(zip(keys, values)))

Surprised !! 😮 😯 😲 yes it is one line. Tell me which method you like in the comment section. And finally if you want the explanation of these solutions please checkout my YouTube Channel: https://youtu.be/PFsP2U4_GH0

How to reverse a list in python?

Afiz — Sun, 02 Jan 2022 17:11:12 +0000

How do you reverse a list in Python?

There are 2 good ways to reverse a list.

Slicing
reverse method

1. Slicing: Generates new list and original list won't be updated.

In [1]: chars = list('abdbbef')

In [2]: chars[::-1]
Out[2]: ['f', 'e', 'b', 'b', 'd', 'b', 'a']

2. Reverse method: `reverse` method modifies the original list.

In [3]: chars.reverse()

In [4]: chars
Out[4]: ['f', 'e', 'b', 'b', 'd', 'b', 'a']

Which method do you prefer? Share your views in the comments.