DEV Community: sleeks.creates.dev

Modern Data Structures and Algorithms With Python.

sleeks.creates.dev — Wed, 05 Apr 2023 18:14:49 +0000

This is a piece that is a continuation of my second article python-101-a-step-by-step-python-tutorial-guide-for-beginners If you're not so sure or wondering, click the above link so that you can see the article and learn Python programming language the right way.
In this article, We will go all the way in talking about data structures which are very crucial in organizing the storage on your computer, allowing you the ability to access and change your data very easily. Consequently we will also discuss the many types of Data Structures used in Python, for example Lists, Tuples, Dictionaries, Sets, Stacks, Queues, Linked list and so on.

Introduction To Data Structures and Algorithms Using Python.

What is a Data Structure?

Is a set of procedure that allows you to define, store, access and manipulate data.
A Data structure is an organized collection of data in your computer or a logical model or mathematical model that of a particular organization of data.
Data structure is important since it defines the relationship between the elements of the data stored in memory.
A data structure is a data composed of a set of functions and a set of statements.

An Algorithm in Python?

An Algorithm is a finite sequence of rules or instructions, each carrying a clear meaning that one must perform to solve a well-formulated problem.
Python Algorithm is important because they have a detailed set of instructions that facilitates the processing of data for a specific purpose.

Types of Data Structures in Python.

There are two types, namely:

Built-in Data Structures
User-Defined Data Structures

Built-in Data Structures

They comprise the following; Lists, Tuples, Dictionaries and Sets.

User-Defined Data Structure

These data structures include Stack, Queues, Graphs, Lists, Trees and HashMap

Additionally, In Python, Data Structure can be categorized into two different groups this is Linear and Non-Linear Data Structures where in the Linear data structure the data items or elements are arranged or stored in a linear sequence for example Lists, Stack, Queues etc whereas in Non-linear Data Structure the data item or node is linked to multiple numbers of items or elements say 'n' for instance Tree and Graphs.

Lists

A list is a simple way to give one name to a collection of values. These values or elements can have different data types i.e int, float, complex numbers, strings etc and even other lists.
Lists allow you to use several elements at once with all the information stored in that list and is created by placing elements inside square brackets [], separated by commas.

Python 3.10.2 (main, April 4, 09:03:01) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for
>>> mylist = [Ruby, Vue, NodeJs, Flask, Perl]
>>> my_list = [1, "Hello World", 3.14]
>>> my_nested_list = ["Jatelo", [9, 10, 11], ['x']]
>>> print(mylist)
>>> print(my_list)
>>> print(my_nested_list)

Output:

[Ruby, Vue, NodeJs, Flask, Perl]
[1, "Hello World", 3.14]
["Jatelo", [9, 10, 11], ['x']]

List items are ordered, changeable or mutable, and allow for the values to be duplicated.
A list indices start at 0, and lists can be sliced, concatenated and so on.
An indexed list can be accessed by referring them using an index number and it is important to note that a list having 3 elements will have an index from 0 to 2.

months = ["January", "February", "March"]
print(months[0])  
print(months[1])  
print(months[2])

Output:

January
February
March

In Python, negative indexing means start from the end
-1 refers to the last item, -2 refers to the second last item and -3 refers to the third last item etc.

colors = ["red", "orange", "yellow", "green", "blue", "indigo", "violet"]
print(colors[-1])
print(colors[-3])
print(colors[-5])

Output:

violet
blue
yellow

To remove an item in a list, you can use either use the del statement if you know exactly which item(s) you are deleting or the remove() method which removes the specified item.

days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
del days[2]
print(days)
days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
del days[1:3]
print(days)
days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
del days
print(days) 

days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
days.remove("Wednesday")
print(days)
days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday"]
days.pop(1)
print(days)

Output:

['Monday', 'Tuesday', 'Thursday', 'Friday']
['Monday', 'Thursday', 'Friday']
Traceback (most recent call last):
  File "/tmp/sessions/20b16bb7e7902bfb/lis.py", line 11, in <module>
    print(days) 
NameError: name 'days' is not defined
['Monday', 'Tuesday', 'Thursday', 'Friday']
['Monday', 'Wednesday', 'Thursday', 'Friday']

In a List, for you to slice a range of items you must use the slicing operator [:].

cars = ["Ford", "Tesla", "Toyota", "Mustang", "BMW", "Volvo"]
print(cars[3:4])
print(cars[5:])
print(cars[:])

Output:

["Mustang"]
["Volvo"]
["Ford", "Tesla", "Toyota", "Mustang", "BMW", "Volvo"]

To add a single item to a list, you will have to use the append() method or add multiple items using the extend() method.

odd = [1, 3, 5]
odd.append(7)
print(odd)
odd.extend([9, 11, 13])
print(odd)

Output:

[1, 3, 5, 7]
[1, 3, 5, 7, 9, 11, 13]

Tuples

Similar to a List, A tuple is used to store multiple items in a single variable.
The main difference between tuples and lists is that you cannot change or modify the elements of a tuple hence tuples are Immutable once it is assigned whereas you can change the elements of a list making them have mutable functionality.
A tuple is created by placing all the elements inside parentheses (), separated by commas. Although, the use of parentheses in tuples is optional.
A tuple can have any number of items and they may be of different types such as integer, float, list and string.

Python 3.10.2 (main, April 4, 09:13:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for
>>> tuple_1 = (0, 1, 2, 3, 4, 5)
>>> tuple_2 = ("Zawadi Zoe", 4.5, [a, b, c] )
>>> tuple_3 = ([4, 2, 3],"Marvelous Day!", ['z'])
>>> print(tuple_1)
>>> print(tuple_2)
>>> print(tuple_3)

Output:

(1, 2, 3, 4, 5, 6, 7)
("Zawadi Zoe", 4.5, ["a", "b", "c"])
([4, 2, 3],"Marvelous Day!", ["z"])

An example of a tuple created without using parentheses:

mytuple= True, False, True
print(mytuple)

my_tuple = "a", "b", "c"
print("a")
print("b")
print("c")

Output:

(True, False, True)
a
b
c

Tuple items are ordered, unchangeable, and allow duplicate values.

my_tuple = ("hi",)
print(type(my_tuple))

my_tuple = ("hi")
print(type(my_tuple))

Output:

<class 'tuple'>
<class 'str'>

In the above example, you will need to use a comma to tell Python that you are creating a tuple with a single item, otherwise, Python will not recognize it as a tuple.

To access an items in a tuple always use the index operator [], where the index starts from 0.

mytuple = ("Batman", "Superman", "Ironman", "Fishman", "Mudraman")    
print(mytuple[4])

Output:

Mudraman

Negative indexing in Python tuples is similar to that one on lists.
The index of -1 refers to the last element, -2 to the second last element etc, Confirm the shared example on List which is similar to a Tuple.

Once the tuple is created, you cannot change its values as a result of its unchangeable/immutable functionality, however, you can convert the tuple into a list, change the list, and convert the list back into a tuple.

mytuple = ("Manganese", "Lead", "Copper", "Iron", "Gold")
b = list(mytuple)
b[1] = "Silver"
mytuple= tuple(b)
print(mytuple)

Output:

("Manganese", "Silver", "Copper", "Iron", "Gold")

To access a range of elements in a tuple by using the slicing operator colon [:].

mytuple = ("Manganese", "Lead", "Copper", "Iron", "Gold", "Bronze")
print(mytuple[1:4])
print(mytuple[:-4])
print(mytuple[4:])
print(mytuple[:])

Output:

('"Lead", "Copper", "Iron")
("Manganese", "Lead")
("Gold", "Bronze")
("Manganese", "Lead", "Copper", "Iron", "Gold", "Bronze")

For concatenation or combining two tuples then you can use the + operator.

tuple1 = ("x", "y" , "z")
tuple2 = (1, 2, 3)
tuple3 = tuple1 + tuple2
print(tuple3)

Output:

("x", "y" , "z", 1 , 2 , 3)

In Python, to repeat elements in a tuple for a given number of times then use the * operator.

Both + and * operations result in a new tuple.

color = ("red", "orange", "yellow")
tuple4 = color * 2
print(tuple4)

Output:

("red", "orange", "yellow", "red", "orange", "yellow")

Since you cannot change the elements in a tuple. This means that you cannot delete or remove elements from a tuple.
To delete the entire tuple use the keyword del.

thistuple = ("Lemon", "Onion", "Cadamon",)
del thistuple
print(thistuple) 

thistuple = ("Mango", "Grapes", "Banana", "Avocado")
b = list(thistuple)
b.remove("Banana")
thistuple = tuple(b)
print(thistuple)

Output:

Traceback (most recent call last):
  File "/tmp/sessions/09e0f94d526221f8/thistup.py", line 3, in <module>
    print(thistuple) 
NameError: name 'thistuple' is not defined
("Mango", "Grapes", "Avocado")

Dictionaries

A Dictionary is a collection of items where each item of a dictionary has a key/value pair that stores data values in those key/value pairs.
Keys are unique within a dictionary while values may not be. The values of a dictionary can be of different types, but the keys must be of an immutable data type such as strings, numbers, or tuples.
A dictionary is like an associative array where each key stores a specific value and cannot be indexed by a sequence of numbers but indexed based on keys.
To create a dictionary just place items inside curly brackets {} and separate them with commas.

Python 3.10.2 (main, April 4, 10:11:01) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for
>>> pop = [1.4, 332, 1.42]
>>> countries = ["India", "USA", "China"]
>>> world = {"India":1.4, "Usa":332, "China":1.42}
>>> print(world)
>>> dict = {"brand": "Audi", "model": "Q5", "year": 2023}
>>> print(dict)
>>> mydict = {"name": "Utumishi Tech", 1: ["a", "b", "c"]}
>>> print(mydict)
>>> my_dict1 = dict({1:"Gold", 2:"Silver"})
>>> print(my_dict1)
>>> my_dict2 = dict([(1,"Gold"), (2,"Silver")])
>>> print(my_dict2)

Output:

{"India":1.4, "Usa":332, "China":1.42}
{"brand": "Audi", "model": "Q5", "year": 2023}
{"name": "Utumishi Tech", 1: ["a", "b", "c"]}
{1:"Gold", 2:"Silver"}
{1:"Gold", 2:"Silver"}

Dictionaries cannot have two items with the same key and thereby when items are duplicated on a key it overwrites the existing value.

dict = {"brand": "BWM", "model": "M2 G87", "year": 2022, "year": 2023}
print(dict)

Output:

{"brand": "BWM", "model": "M2 G87", "year": 2023}

As a result of dictionaries being mutable then you can be able to add a new item or change the value of existing items using an assignment operator. In any case, if the key is already present, then the existing value gets updated and if not a new (key: value) pair is added to the dictionary.

mydict = {"name": "Zawadi", "age": 18}
mydict["age"] = 19
print(mydict)
mydict["address"] = "Harlem, New york"
print(mydict)

dict = {"brand": "BMW", "model": "G5", "year": 2023}
dict["color"] = "blue"
print(dict)

Output:

{"name": "Zawadi", "age": 19}
{"name": "Zawadi", "age": 19, "address": "Harlem, New york"}
{"brand": "BMW", "model": "G5", "year": 2023, color: blue}

You can either remove individual dictionary elements or clear the entire contents of a dictionary. Also, you can delete the entire dictionary with a single operation.

A pop() method which removes the item with the specified key name:

dict = {"name": "Zawadi", "age": 18, "DOB": 2003, "country": "Ghana"}
dict.pop("DOB")
print(dict)

Output:

{"name": "Zawadi", "age": 18, "country": "Ghana"}

The clear() method empties the dictionary:

dict = {"name": "Zawadi", "age": 18, "DOB": 2003, "country": "Ghana"}
dict.clear()
print(dict)

Output:

{}

The pop item() method removes an arbitrary item and returns (key, value)

dict = {"name": "Zawadi", "age": 18, "DOB": 2003, "country": "Ghana"}
dict.popitem()
print(dict)

Output:

{"name": "Zawadi", "age": 18, "DOB": 2003}

The del keyword removes the item with the specified key name and can also delete the entire dictionary completely:

dict = {"name": "Zawadi", "age": 18, "DOB": 2003, "country": "Ghana"}
del dict["age"]
print(dict)

Output:

{"name": "Zawadi", "DOB": 2003, "country": "Ghana"}

dict = {"name": "Zawadi", "age": 18, "DOB": 2003, "country": "Ghana"}
del dict
print(dict)

Sets

In a set, a single variable is used to store several items.
In comparison to lists and tuples, sets cannot have multiple occurrences of the same element(duplicates or repeating items) and can store unordered values.
Sets can also be used to perform mathematical set operations like union, intersection, symmetric difference, etc.
Set elements are unchangeable, but you can remove elements and add new elements.
A set is created by using the built-in set() function or placing all the elements inside curly brackets {}, separated by a comma.
Sets can have any number of items including different types like integer, float, tuple and string.

Python 3.10.2 (main, April 4, 10:31:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for  
>>> thisset = {"COVID-19", "typhoid", "malaria", "Pneumonia"}
>>> print(thisset)
>>> myset = {4.3, "Hi", ("x", "y", "z")}
>>> print(myset)
>>> set1 = {"Zawadi", "Mark", 4, 16, 36, True, True, True}
>>> print(set1)

Output:

{"malaria", "COVID-19", "Pneumonia", "typhoid"}
{'Hi", 4.3, ("x", "y", "z")}
{16, True, 4, 36, "Mark", "Zawadi"}

To make a set without any elements, we use the set() function without any argument.

myset = set(("Ghana", "Mali", "Cameroon"))  
print(myset)
myset1 = {"Ghana", "Mali", "Cameroon"}
print(type(myset1))

Output:

{"Mali", "Cameroon", "Ghana"}
<class 'set'>

To remove an item in a set, use the remove(), or the discard() method. If the item to remove does not exist, remove() will raise an error therefore use discard() that will not raise an error.

set1 = {"COVID-19", "typhoid", "malaria", "Pneumonia"}
set1.discard("COVID-19")
print(set1)

Output:

{"Pneumonia", "typhoid", "malaria"}

In Python, to remove the last item in a set use the pop() method:

disease = {"COVID-19", "typhoid", "malaria", "Pneumonia"}
a = disease.pop()
print(disease)

Output:

{"COVID-19", "typhoid", "malaria", "Pneumonia"}

To delete the whole set then you use the clear() method which empties the set:

myset = {"pnemunomia", "typhoid", "malaria", "COVID-19"}
myset.clear()
print(myset)

Output:

set()

Once a set is created, you cannot change its elements, but you can add new items by using the add() method.

even = {2, 4, 6, 8}
even.add(10)
print(even)
even.update([12, 14, 16])
print(even)
even.update([18, 20], {22, 22, 24})
print(even)

Output:

{2, 4, 6, 8, 10}
{2, 4, 6, 8, 10, 12, 14, 16}
{2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24}

STACK

A Stack is a linear list in which insertion and deletion operations are performed at only one end or side of the list/stack.
The principle used in a stack is Last-in First-Out (LIFO).
A stack is a linear data structure in which elements are added and removed from one end, called the top of the stack.
In a Stack, an item is added on top of other items for instance 5 is added on top of 4, 3, 2 and 1 which were already in the stack and when you are removing the elements you have to start with the topmost element for example 5 is removed first then followed by 4.

In Python, stacks the insert operation is known as push and the delete operation is known as pop.

Basic Operations on Stack

empty(): checks and returns if the stack is empty.
size(): checks and return the size of the stack
push(x): adds or inserts the element 'x' at the top of the stack.
pop(): removes or deletes the topmost element found in the stack.
top() reports the reference to the topmost element of the stack.

Creating a Slack using List.

stack = ["North", "South", "West", "East"]
stack.append("North West")
stack.append("North East")
stack.append(1)
print(f" Initial stack : {stack}")

Output

Initial stack : ["North", "South", "West", "East", "North West", "North East", 1]

stack = ["North", "South", "West", "East"]
stack.pop()
stack.pop()
stack.pop()
stack.pop()
print(f" stack after items are removed : {stack}")

Output

stack after items are removed : []

Real-Life Application of Stack

Arrangement of plates on a dining table in the Cafeteria
Cards are arranged on top of the table while people are playing

QUEUES

A Queue is a linear data structure in which insertion takes place from one end called the Back end or Rear and deletion takes place from the other end called the Front end.
Insertion and Deletion takes place from different places.
The principle used in Queue is First-in First-Out (FIFO) where the element that is inserted first is deleted first.
In a Queue there are two variables one is the Back/Rear and the other is the Front.
Elements must be added at the Back/Rear end and removed or deleted at the Front end.

Basic Operations on Queue

Enqueue: Inserts or adds an element to the queue.
Dequeue: Removes or deletes an element from the queue.
Size: Checks whether the queue is empty.
Rear: Checks on the last item from the queue.
Front: Checks on the front item from the queue.

Creating Queue using List

queue = ["North", "South", "West", "East"]
queue.append("North West")
queue.append("North East")
queue.append(1)
print(f" Initial queue : {queue}")

Output

Initial queue : ["North", "South", "West", "East", "North West", "North East", 1]

queue = ["North", "South", "West", "East"]
queue.pop()
queue.pop()
queue.pop()
queue.pop()
print(f" queue after items are removed : {queue}")

Output

queue after items are removed : []

Real-Life Application of Queue

A queue or waiting list of people in a Bank waiting to be served.
A queue or waiting list of people in the Airport waiting to book a flight.
A queue or waiting list of cars in a parking booth.
In Call Center, phone systems use Queues to hold people who are calling in order in an orderly manner.

LINKED LIST

The Linked List is a sequence of nodes having similar data types, each node containing one data object and a pointer to the next node.
A Linked List is implemented by each item having a link to the next item.
In Python Linked List, an item or an element is called a node.The Head points to the first node while the Last node points to the NULL which indicates the end of the chain.

Types of Linked Lists

Singly-linked lists
Doubly linked lists
Circular linked lists
Circular doubly linked lists

Creation of a Linked List

# creating linked list
class LinkedListNode :
      def __init__(self,value, nextNode = None):
        self.value = value
        self.nextNode = nextNode
# creating nodes with their values
Node1 = LinkedListNode("North")
Node2 = LinkedListNode("South")
Node3 = LinkedListNode("West")
Node4 = LinkedListNode("East")
Node5 = LinkedListNode(10)
#directing the nodes to the next data
Node1.nextNode = Node2
Node2.nextNode = Node3
Node3.nextNode = Node4
Node4.nextNode = Node5
#linking the nodes
currentNode = Node1
while True:
  print(currentNode.value, "~>" , end ="")
if currentNode.nextNode is None:
    print(None)
    break
currentNode = currentNode.nextNode

Applications of Linked List

Dynamic memory allocation.
Implemented in stack and queue.
Hash tables, Graphs.
In undo functionality of the software.

Python 101: A Step-by-Step Python Tutorial Guide For Beginners.

sleeks.creates.dev — Thu, 30 Mar 2023 10:12:46 +0000

Introduction to Python Programming Language.

What is Python?

Python is a highly programming language which is:
Open source and community driven: Python is free for everyone to access and use and you have the ability to change the source code to fit your needs
Dynamically typed and interactive: You type Python prompts and directly interacting with the interpreter when writing your programs.*
Object oriented: Python supports Object Orienting method of programming.
Interpreted: Python is compiled and processed at runtime by the interpreter
A Beginner's Choice: Python is easy to learn, read, maintain source code and supports the development of a wide range of programs.

Key Points to Note:

When writing a python program code you have to use the .py extension at the end of your file name for the program to run for instance app.py
It is not necessary to define the type of variable in python and also you don't need to add a semicolon at the end of the statement.
Python uses new lines to complete and run a command, uses whitespace to define scope for example scope of loops, functions and classes. It largely relies on indentation.

History of Python.

In the late 1970s, a programming language called ABC which is a general-purpose programming language is developed at CWI in the Netherlands, Armsterdam.
In the 1980s, Guido Van Rossum joins the ABC team and in the late 1980s he conceptualizes Python.
In 1991, Guido Van Rossum published the first version on Python(0.9.0) at CWI in the Netherlands, Armsterdam.
Guido Van Rossum liked Monty Python Flying Circus and thats why he choose to name the previously developed ABC programming language to Python.

Why Python Programming Language For Beginners?

Python has simple structure, clearly defined syntax and a few keywords therefore allows for beginners to understand it quickly.

   x=4 ; y=8         # Declaring two integers
   z= y - x          # Subtracting two integers
print(subtract)      # Displaying the output

Python written programs can run on a variety of platforms including LINUX, Windows and Mac OS.
Python provides a better structure and support for large programs then shell scripting.
Python has a well, clear and simple syntax with very few lines compared to other programming languages.

 colors =[red, orange, yellow, green, blue, indigo, violet]
 print(colors)

Python support OOP technique of programming therefore you can end up treating it either procedurally or functionally.
Python programs are executable as soon as the program is written meaning it facilitate fast prototyping it is run on an interpreter system.

Important Uses of Python.

Software development and SAAS products: Technology and Software-driven companies use Python for software building and other SaaS products creation.
Mobile Web Creations: Developers use Python to build customer and enterprise mobile app for customer engagement and workforce productivity.
Database access and management: Python is used by many companies to access, connect, read and modify files in the company's database system.
Data Analysis, Data Visualizations and Data Wrangling: Python helps companies to leverage cloud platforms for building solution since it has the ability to handle big data and perform complex mathematics
AI and Automation: With the fast growing AI usage by many companies, Python has been used significant tool in building AI models and variables by a number of companies.
Desktop GUI Applications: Python has been used by organizations to build desktop apps to capture and monitor results from several connected devices.
Education: Software Developer, Data Engineers, Data Scientist and others have learned python as part of their career.
Network programming and IoT solutions.

Python Features

Easy to Learn and Write
Python has a clear syntax with simple structures and fewer lines thus enables you to focus and think of the code mostly.

Portable
You can run Python on a wide range of hardware platforms and has the same interface on all the platforms.

Extendable and Embeddable
You can add and combine other low modules to the Python Interpreter. The modules enables programmers to add to or customize their tools to be more effective as well as efficient at the same time.

Interactive Mode
Since Python supports an interactive mode, You can interact with the interpreter while write your code and also debug the snippets of your code.

A Broad Standard Library and Large Community
Python has many build-it libraries and is compatible with other cross-platforms like UNIX, Windows and Mac OS therefore accessible in any part of the world and you don't have to code everything by yourself.

Databases
Python provides interface to all major commercial databases and you can be able to read, interpret and modify your database using python programs.

GUI Programming
Python supports GUI apps that can be created and ported to many system calls, libraries and windows systems such as Macintosh and Windows MFS.

HOW DO WE INSTALL PYTHON ON YOUR DEVICE?

Once your device is open and set with internet working properly, Click Here and depending on your Operating System of your device then Go and
Select 1 if you are using Windows, Select 2 if you are using Mac OS, Select 3 if you are using UNIX/LINUX and finally Select Others4 if you are using a different OS than the other three mentioned above.
After clicking on the above links and choosing the correct link as per your Operating System, On the same page of that link select the type of version/release you want and click on it for the downloading process to begin.
Once the Installer file has been downloaded, double click on the installer file on your Downloads Folder to run and the installer file and install.

NOTE:

Always ensure you have set up the path of the system variable to allow for easier and swift execution of the python file plus the appropriate environment storage variable is set correct For more information click To Read More on PATH VARIABLE Set-up
*You can install Integrated Development Environment (IDEs) on your device or language programming interpreters like VS Code, Sublime text or even Notepad++ where you can run and execute your Python programs. PyCharm,
JupyterNoteBook, Spyder, Visual Studio, Google Collab

How Do We Confirm Whether Python is Fully Installed in You Device?

1.Windows User
On your device search box next to the START Menu type and search in cmd for Command Prompt then run this command line:

C:\User\Zawadi python --version

2.Mac OS User
On your Mac device open up the terminal and type:

python --version

3.UNIX/LINUX
While on Unix or Linux open your terminal and type the command:

Zawadi@Ubuntu python --version

If you receive back a feedback say 'Python is Not Found' after typing the above command then that implies that Python has not been install in your device, so what you do click HERE again to download and access it on your device.
Once you run the above command line and obtain the following output:

C:\User\Zawadi python --version
Python 3.11.2
C:\User\Zawadi

that means Python has now been installed in your device.

Our First Python Code.

Once python is now installed on your device you can now start to write your own python programs on your device.

You can start with a simple python program named myprogram_one that gives the following output: How are you feeling Today?

Go on your favorite IDE or text editor and save it as myprogram_one.py

   print(How are you feeling Today?)   # First Print Statement
   print(Awesome)                     # Second Print Statement

Then run the file which will produce the output:

   How are you feeling Today?          # First declared output
   Awesome                            # Second declared output

Python Keywords and Identifiers.

Keywords in Python

Python keywords are predefined reserved words that have a special meaning to the interpreter or compiler.
They can never be assigned to identifiers.
Some example of keywords include def, class, while, if, else, true, lambda, nonlocal, false e.t.c

Python Identifiers

Python identifiers are names used to identify variables, functions, classes, modules or other objects.
You must never assign Python keywords as the name of your identifiers.
NB:

Identifiers start with A to Z or a to z or an underscore(_) followed by letters or digits from 0 to 9 example Fullname, fullname, full_name, data_34 or _file1
Python is case sensitive meaning that Birthdate and birthdate are two separate identifiers one starting with upper case while the other one starts with a lower case.
In Python, Identifiers must never be keywords because the interpreter already knows Python keywords and using them as identifiers can lead to syntax errors
Python does allow the use of special characters thus your identifers must not have space characters for instance &Age, day-1, year%100, @my.net

Literals in Python

Literals are data or constant values stored in variables.
In Python, when you assign a constant value 10 to a variable 'a' the value is stored in 'a'. 10 which is an integer value is called Integer Literal
Python supports the following literals

Numeric Literals
They comprise of int (integer):10 , long (long integer)314215869, float(floating integer):-22.7 and complex(complex numbers):3.142j
String Literals
is formed by enclosing a text with a single or double quotes '' "" example "Tap" , '123456'

 text1 = "Hello"  # single line string
 text2 = 'Hello\  # multi line string
           Team'
 text3 = '''How do you #string with triple quotation marks
         do
         today?'''

Boolean Literals
They are True or false.
Special Literals
Python has only on special literal, None which you can use to specify when the field is not created and also use it at the end of lists.

Python Statements and Comments.

A Python statement instructs the python interpreter to run or execute a given program. They include: if while and for statements Where you want to use various statement in your program then always use brackets[], braces{} or parentheses() and suppose you want to get two or more statement from a single line statement you use a semi-colon.

if statement

age = int(input(enter your age))         # input age     
print("Your age is", age)

if age > 18                         # checking eligibility
print(You can take part in voting process)
else:
print(You cannot take part in voting process)

while statement

   a = 20
   b = 15
while a >  0 and b > 0 :
   a -= 3
   b -= 2
print{(a , b)}

for statement

for value in range(1,10)
print(value)
print(Today is my birthdate)

Python Indentation

Indentation refers to the spaces at the beginning of the code line. In Python, Indentation is something you use to define a block of codes take for instance a simple
if statement

x=4
y=8
if y > x :                  # statement ends with colon
    x = 8                   # whitespace showing indentation
    y = 16
print(sum(x , y))

In this statement it ends with a colon and whitespace is used (indentation) to describe what takes place in the case of a statement. In Python the end of a line is the same as the end of a statement. Also it is important for you to remember when you are using indentation be keen and consistent throughout your code to avoid getting syntax error.

Python Comment
Gives an explanation and description of a certain python code. You use the # symbol at the start of the statement to denote a comment. You can place it at the start after the code in the same line or at the end of the line Python will still ignore both of them while executing the program.

#This is a comment
print(Dear Team)           # This is a comment

Dear Team                   # output

A Comment is not only supposed to give the explanation of the code but also can be used to prevent the python code from executing.

#print(What is my name?)         # Ignores this line declared
print(My name is John Doe) # declared statement to be executed

My name is John Doe       # output from the declared statement

For multiple comments, you either use # symbol on each line or triple quote ''' / """ which is a multi-line string

'''This is an example of a
set created by a team in
Juxpoints.edu.ac.uk'''
set4 = (python, java, react, ruby, perl, kotlin)
print(len(set4))

#This is one type of a
#multi-line comment that
#goes to the next page
print(I love to code everyday.)

Python Variables

Variables are nothing more than reserved memory location to store value which means that when you create a variable reserve some space in memory.
Based on the data type of the variable, the compiler allocates memory and decides what can be stored in the reserved memory thus by assigning different data types to variable you are able to store integer, decimals and character in these variable.
The declaration of python happens automatically when you assign a value to a variable using the equal sign = which assigns value to the variable.
The operand to the left is the name of the variable whereas the operand to the right is the value stored in the variable

age = 45
distance = 11.11
name = "Zawadi"

print(age)
print(distance)
print(name)

In the above example, 45, 11.11 and "Zawadi" are values assigned to age, distance and name variables respectively.
With python you can assign a single value to several variable simultaneously as well as as multiple objects to multiple values.

y = m = c = 10
print(y)
print(m)
print(c)

y, m, c = 2, 3.14, "Shakti"
print(y)
print(m)
print(c)

Python Operators

Operators in Python allows for the processing of variables and value. Two or more numerical values can be added subtracted, multiplied or divided to give out a new output
Python supports the following operators:

Arithmetic Operators In python, you perform your mathematical operations using + (addition) , - (subtraction), // (quotient), / (division), %(modulus) and so forth and so on. for example:

   a = 9
   b = 27
print(a + b)          # Addition
print(a - b)          # Subtraction
print(a * b)          # Multiplication
print(a / b)          # Division
print(a % b)          # Modulus
print(a // b)         # Quotient
print(a ** b)         # Exponent

Assignment Operators You assign values or content of the variable to the variable using assignment operators.

m = 7             # assigning value to m
c = m             # assigning value of m to c
y = m + c - 3     # execute the expression and find value of y
print(m)
print(c)
print(y)
m += 7
c -= 7
y *= 7
print(m)
print(c)
print(y)
m /= 4
c %= 4
y //= 4
print(m)
print(c)
print(y)

Comparison Operators In Python, you can compare the value of two variables and the result is a Boolean value either true or false.

p = 12
v = 18
print(p == v)   # if p and v are equal then output is true 
print(p != v)   # if p and v are not equal then output is true
print(p > v)    # if p is greater than v then output is true
print(p < v)    # if p is less than v then output is true
print(p >= v)   # if p is greater than or equal then output is true
print(p <= v)   # if p is less than or equal then output is true

Relational or Logical Operators You can combine two or more comparison operations using Logical or Relational Operators and the output value is a Boolean value i.e True or False

x = 2
y = 4
print(x > 3 and y < 5) # if both conditions are true output is true
print(x > 2 and y < 6) # if both conditions are true output is true

Membership Operators Python's membership operator tests for membership in a sequence such as strings, lists or tuples.

fruits = [apple, mango, banana, orange, guava]
print("tunip" not in fruits)
#output is true since in the sequence with value "tunip" is not in the list

Identity Operators Identity operators are used to check if the location or address of two variables is the same or not.

a1 = 3
b1 = 3
a2 = 4
b2 = 5
a3 = [10, 3.14, "Zawadi"]
b3 = [10, 3.14, "Zawadi"]
print(a1 is not b1) # output is false
print(a2 is b2)     # output is false
print(a3 is b3)     # output is true

Bitwise Operators In Python you can use Bitwise operators to perform a bit by bit operation among given operands.

z1 = 4
z2 = 5
print(~z1)
print(z1 in z2 =', z1 & z2)
print(z1 ^ z2)
print(z1 | z2)
print(z1 << z2)
print(z1 >> z2)

Python Data Types

Data Types in Python include:

Numeric type(numbers)
integer(int) i.e 10, 8 ,6
float i.e 3.14, 37.5
complex numbers i.e 12 + 20j, 13 +30i
Dictionary
{'x': 4, 'y' : 8}
Boolean
True or False
Sequence type i.e
string e.g
list e.g ["Zawadi", 24, Korea", 6.4]
*tuple*e.g((a, b, c) ,10 ,3.147j)
Set
{"Hello World", 12345, (x, y, z)}

Python Loops

In a loop, statement are executed following the sequence the code is written the first statement of the function is executed first then followed by the second statement then third statement and so on.

1.For Loop
In Python, For loop is the simplest form of repetition. A For Loop repeats a group of statement a specified number of times.

cars = ["BMW", "Rolls Royce", "Toyota", "Tesla", "Honda"]
for i in cars:
      print(i)

You can loop in string because a string has sequence of characters.

for x in "Demitrius":
          print(x.capitalize())

You can introduce Else Statement in your For Loops but it is optional and that Else part is executed by the interpreter once it has run all the elements in the sequence.

for i in range(7):
      print(i)
else:
     print('The range ends here')

In Python, For Loops allows Continue Statement in its structure which you can use to stop the current iteration of the loop, and go to the next:

r = trolls
for x in r:
      if x == 'n':
           continue
        print(x)

2.Nested Loops
Nested loops are loops found inside another loops.
What the interpreter does when a nested loop program is run is it executes the Inner Loop first and it is executed one time for each iteration of the Outer Loop

names = ["Bingo", "Zawadi", "Dalton"]
scores = ["50", "75", "68"]

for a in names:
  for b in scores:
       print(a , b)

3.While Loop
While Loops are similar to If statement in that the code is executed when the condition or expression is true, the only difference between the two is that While Loop continue to execute the code repeatedly as long as the condition is true as opposed to if statement.

a = 4
while a < 12:
      a += 1
      print(a)

You can add an else block on your while loop which is going to be executed if the condition is false or all the conditions have been met.

count = 7
while count > 0:
      print(Hello Python)
 else:
     print(End of cycle)

In Python you can also use break statement to stop the while loop even if the condition is true and continue statement to skip the current iteration and continue with the next.

y = 1
while y < 8:
     if y == 6:
         break
     print(y)

y = 1
while y < 8:
      y += 1
     if y == 4:
          continue
     print(y)

Python Conditional Statements

These statements are based on if statement that executes the code after check if the condition is satisfied or the given expression is true

passmark = 78

if passmark < 45
print("Student failed the test, try again.")
# Output Student failed the test, try again since the expression is true

In the above example if the condition was not satisfied i.e false then you will not get an output.

In the If Else statement if the condition is false the interpreter will move to the next code line.

user = input('Enter your username')
password = input('Enter your password')
if user == 'Zawadi' :
       print('Welcome' , user)
else:
     print('incorrect username')

age = 35
if age == 35 :
    print('Adult')
else:
    print('Teenager')

In the Else If statement the interpreter runs on multiple conditions:

a = 4
if a == 1:
     print('One')
elif a == 2:
     print('Two')
elif a == 3:
     print('Three')
elif a == 4:
     print('Four')
else: 
     print('Out of range')

In the next article We will be continuing with Introduction to Data Structures in Python such as Lists, Tuples, Dictionaries, Sets, Stacks, Queues as we know Data plays a critical role in Web Development, Machine Learning Artificial Intelligence and Automation. STAY TUNED!!!

Mastering Python For Web Development.

sleeks.creates.dev — Sun, 01 May 2022 15:26:51 +0000

How can an aspiring developer master Python for web development in today's world? Reading books, documents, blog posts or articles relating to the subject matter? Watching online tutorials? Attending class of web development physically? or Practicing everything that you learn on web development?
Any learning technique that enables you to get the best out of yourself while learning is what any learner should prefer to use to become a master/great programmer.
Python, being a practical language, it offers a concise and clear syntax which is easy to write and understand. Most developers and learners prefer Python for web development since it is a very powerful tool which has been used to back some of the world's most common products and services.
Python offers many frameworks used in web developments such as Django, Flask, Cherrypy, Pyramid, web2py, and Turbogears that has been used by power some of the most successful websites such as Google, Netflix, NASA and many more.
In order to master Python for web development visit as many online learning platforms like Cousera, Freecodecamp.org, Udemy, Future learn, W3schools and IBM to be conversant with different Python coding information out there. In addition to that Youtube tutorials on Python and other learning documentations of various frameworks will be helpful to you.
In this article, I will discuss Mastering Python for web development using Django where I show you how to create and develop a web project and so much more.

Reasons for Using Python For Web Development.

Django is published under BSD license, which assures the web applications can be used and modified freely without experiencing problems. It is free and open source.
Django integrates a lot of efficient ways to perform unit tests.
Django is fully customizable, developers can adapt to it easily by creating modules or overridden framework methods.
Uses the Don't Repeat Yourself (DRY) principle which keeps the code simple and clear without having to copy/paste the same code elsewhere.
Using python in this framework allows you to have benefits from all Python libraries and assures a very good readability.
Django is supported by a good community which means that you can easily resolve issues and fix bugs quickly as a result of many code examples that shows good practices.

Django Framework

Django is a high-level python web framework that allows rapid development and clean practical design which was released in 2005 and named after a jazz guitarist Django Reinhardt.
It was first started in 2003 by Adrian Holovaty and Simon Willison as an internal project at Lawrence Journal-World newspaper and was released in July, 2005.
Using Django it is easier to build a better web app faster and with less code plus its free and open source.

Features of Django

Complete: Strives to provide almost everything that developers require to help them develop their sites from consistent design patterns to extensive updated documentations.
Versatile: Some organizations uses Django to build all sort of things from content management system to social networks to scientific computing platforms to new sites.
Secure: Emphasizes on security by assisting developers to avoid many common mistakes by providing a framework to protect the website automatically. Also gives a secure way to manage user accounts and passwords.
Scalable: Many of the busiest websites uses Django's ability to quickly and flexibly scale to meet the heaviest traffic demands.
Maintainable: Applies design principles and patterns that encourage the creation of maintainable and reusable code. By making use of Don't Repeat Yourself (DRY) principle so there is no unnecessary duplication, reducing the amount of code.
Portable: written in Python which runs on multiple platforms including Windows, Linux, Mac OS applications plus Django is well supported by many web-hosting providers that provides specific infrastructure and documentation for hosting Django sites.

Django Installation Process

In order to be able to use Django, you need to install the following Softwares:

Python
PIP which facilitates the installation of Django and other important packages
Django
Virtual environment

Installation of Python

Depending on the operating system, Windows, Unix/Linux and Mac OS Python can be installed on each operating system.
For an elaborated step-by-step installing process of Python on your P.Cs make sure to check my article on Ultimate Python Tutorial Guide For Beginners.

Installation of PIP

PIP is important as it handles the packages installation, performs updates, and removes all the Python package extensions.

Windows
Download it from Here
Then you install PIP from executable and remember to choose the correct python installation folder.

Unix/Linux
Run the following commands to be able to install PIP.

root@sleekscreations: wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py
root@sleekscreations: python3 get-pip.py

Mac OS
Open up your terminal and run the get-pip.py file as shown below.

$ curl -O https://raw.github.com/pypa/pip/master/contrib/get-pip.py
$ sudo python3 get-pip.py

Note that:
To confirm whether pip is installed in your P.C, open your terminal and run the command pip --version or pip3 --version. If you get the pip version then it is safe to say that it has been installed.

sleekscreations@sleekscreations:~ $ pip --version
pip 20.3.4 from/usr/lib/python3/dist-packages/pip (python 3.9)
sleekscreations@sleekscreations:~ $ pip3 --version
pip 20.3.4 from/usr/lib/python3/dist-packages/pip (python 3.9)

In any case you are not getting any result after executing the above command or you did manage to install pip run the command sudo apt install pip or sudo apt install pip3 on your terminal

Installation of Django

Django for Windows
To install Django with PIP, open command prompt then go to Scripts directory where Python folder is and install Django by running the below command.

C:\Python33\Scripts\pip.exe install django=="X.X"

Django for Linux
At the root level on your terminal execute the following codes.

root@sleekscreations: compgen -c | grep pip
root@sleekscreations: alias pip=pip-3.2
root@sleekscreations: pip install django=="1.6"

Django for Mac OS
We install Django by running the command pip install django=="1.6" on the terminal.

$ cd usr/local/bin
ln -s ../../../Library/Frameworks/Python.framework/Version/3.3/bin/pip3
pip
$ pip install django=="1.6"

Installing Virtual Environment(Virtualenv)

We are creating a virtual environment to have a separate working environment for our new project.
In order to install virtualenv, lets run pip or pip3 then using PIP we run pip install virtualenv.
To check if virtualenv is installed the run the command virtualenv--version.

sleekscreations@sleekscreations:~ $ virtualenv--version
virtualenv 20.10.0

Creating Our First Project with Django

Before we start to use Django, lets create a folder/directory for this project on the Desktop by running the following command on the terminal.

sleekscreations@sleekscreations:~ $ pwd
user/home/sleekscreations
sleekscreations@sleekscreations:~ $ ls
Desktop Documents Downloads Pictures Music 
sleekscreations@sleekscreations:~ $ cd Desktop/
sleekscreations@sleekscreations:~ Desktop $ mkdir demo_django
sleekscreations@sleekscreations:~ Desktop $ ls
demo_django
sleekscreations@sleekscreations:~ Desktop $ cd demo_django
sleekscreations@sleekscreations:~ Desktop/demo_django $

Under our new directory, lets create virtual environment by using the command virtualenv

sleekscreations@sleekscreations:~ Desktop/demo_django $ virtualenv env

Make sure you activate the environment using source /bin/activate.

sleekscreations@sleekscreations:~ Desktop/demo_django $ source env/bin/activate

Inside our same created directory lets install Django by running pip install django.

sleekscreations@sleekscreations:~ Desktop/demo_django $ pip install django
Collecting django
  Using cached Django-4.0.2-py3-none-any.whl (8.0 MB)
Collecting sqlparse>=0.2.2
  Using cached sqlparse-0.4.2-py3-none-any.whl (42 kB)
Collecting asgiref<4,>=3.4.1
  Using cached asgiref-3.5.0-py3-none-any.whl (22 kB)
Installing collected packages: sqlparse, asgiref, django
Successfully installed asgiref-3.5.0 django-4.0.2 sqlparse-0.4.2

Lets begin our project by running the command django-admin startproject django_project1 which will create our project files on django_project1 and manage.py file.

sleekscreations@sleekscreations:~ Desktop/demo_django $ django-admin startproject django_project1
sleekscreations@sleekscreations:~ Desktop/demo_django $ ls
django_project1 env manage.py

Now let make columns and tables in the database using the migration and migrate commands ./manage.py makemigrations and then ./manage.py migrate.

[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $ ./manage.py makemigrations
[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $ ./manage.py migrate   #copy all migrations to the database
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
  Applying contenttypes.0001_initial... OK
  Applying auth.0001_initial... OK
  Applying admin.0001_initial... OK
  Applying admin.0002_logentry_remove_auto_add... OK
  Applying admin.0003_logentry_add_action_flag_choices... OK
  Applying contenttypes.0002_remove_content_type_name... OK
  Applying auth.0002_alter_permission_name_max_length... OK
  Applying auth.0003_alter_user_email_max_length... OK
  Applying auth.0004_alter_user_username_opts... OK
  Applying auth.0005_alter_user_last_login_null... OK
  Applying auth.0006_require_contenttypes_0002... OK
  Applying auth.0007_alter_validators_add_error_messages... OK
  Applying auth.0008_alter_user_username_max_length... OK
  Applying auth.0009_alter_user_last_name_max_length... OK
  Applying auth.0010_alter_group_name_max_length... OK
  Applying auth.0011_update_proxy_permissions... OK
  Applying auth.0012_alter_user_first_name_max_length... OK
  Applying sessions.0001_initial... OK

Consequently, as we are working on the project's main container directory on the manage.py file lets run ./manage.py runserver which runs on port 8000 by default but if we specify the port number it won't run on default e.g ./manage.py runserver 7000

[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $ ./manage.py runserver
Performing system checks...

System check identified no issues (0 silenced).
May 1, 2022 - 10:51:11
Django version 4.0.2, using settings 'django_project1.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

Next, visit https://127.0.0.1:8000/ which will display the page shown below.

Another method is by running the server on a shared IP address to enable people within the network to be able to view your project.

Lets run ifconfig to check ip and interphase.

[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $ ifconfig
eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether d8:9d:67:cb:cf:96  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 17931  bytes 4982556 (4.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 17931  bytes 4982556 (4.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

usb0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.42.220  netmask 255.255.255.0  broadcast 192.168.42.255
        inet6 fe80::70d8:a7f:4daf:43f7  prefixlen 64  scopeid 0x20<link>
        ether 2a:52:c0:42:23:3b  txqueuelen 1000  (Ethernet)
        RX packets 764  bytes 205457 (200.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 828  bytes 165938 (162.0 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

In our case here we will have to copy the IP address 192.168.42.255 on the same interphase usb0.
Now using manage.py runserver :
Lets run ./manage.py runserver 192.168.42.220.80

[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $ ./manage.py runserver 192.168.42.220:80                                 
Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).
February 10, 2022 - 05:07:08
Django version 4.0.2, using settings 'Django_Project.settings'
Starting development server at http://192.168.42.220:80/
Quit the server with CONTROL-C.

On the terminal to create a superuser run Python3 manage.py createsuperuser or ./manage.py createsuperuser and fill in the name the user, give an email, and set a password. Now, running your server ./manage.py runserver it will allow you to access the Django admin panel for your project.

[env] - sleekscreations@sleekscreations:~ Desktop/demo_django $
./manage.py createsuperuser                                             
Username (leave blank to use 'Sleekscreations'): admin
Email address: admin.admin@outlook.com
Password: 
Password (again): 
Superuser created successfully.

Now try visit https://127.0.0.1:8000/admin to check if you can be able to log in on the login admin page.

Login page for Admin
Fill out your details on the page i.e., the username and password that we created earlier:

Admin page:
View your admin panel afterward on the page below.

For more information to master Django for web development check out: