First Steps in Python Programming

First Steps into Python Programming
Facilitator: Agbo Dozie

This May
Come to
Mind…
when
you hear
Python

Table of Content
1
2
3
4
5
6
7
8
Python. Installation. Practical Uses
Why Python?
Variables, Datatypes (Strings,
Int, Float, List, Tuples, Bool, and
Dictionaries) & Formatting
Functions & Recursions in Python
Arithmetic Operators, Comparators,
Loops, & Conditionals
File Handling in Python
Modules in Python
Project & Setup Github

1
Python,
Installation &
Practical Uses

| Python. IDEs. Installing Python
What is Python?
of significant whitespace, as well as the DRY (Don’t Repeat Yourself) principle.
Wikipedia (Modified)
Installing Python is generally easy, and nowadays many Linux and UNIX distributions include a
recent Python. Even some Windows computers (notably those from HP) now come with
Python already installed. To check if you have Python on your computer, just open your
command prompt and type “Python”. You would see the result below, otherwise you do not
have Python installed.
In order to download Python however, visit the official Python website
https://www.python.org/downloads/ and download the latest version. During installation,
watch out and ensure to check the box labeled “Add Python to PATH”.
Installing an IDE
Installing Python
IDEs are the environment in which we would write Python codes. Python comes
with its default IDE called IDLE, which like the acronym IDE also stands for
“Integrated Development Environment”. Below are some of the most common
IDEs. From VSCode to Atom Editor to PyCharm, and to the very lightweight Sublime
Text.
Python is an interpreted, high-level, general-purpose
programming language. Created by Guido van Rossum
and first released in 1991, Python's design philosophy
emphasizes code readability with its notable use

| Practical Uses of Python
Web Development
Python can be used to make web-
applications at a rapid rate using
frameworks, such as Flask and Django.
Game Development
There are libraries such as PySoy and
PyGame which is a 3D game engine
supporting Python 3.
Machine Learning & AI
Machine Learning and Artificial
Intelligence are the talks of the town as
they yield the most promising careers for
the future.
Data Science & Data
Visualizations
Libraries such as Pandas, NumPy help
you in extracting information. We can
also use libraries like Matplotlib and
Seaborn for visualizations.
Desktop GUI
Python can be used to program desktop
applications. It provides the Tkinter
library that can be used to develop user
interfaces.
Webscraping Applications
Python can be used to pull a large
amount of data from websites which can
then be helpful in various real-world
processes.
Business Applications
Business Applications cover domains
such as e-commerce, ERP and many
more.
Audio & Video Apps
Python can be used to develop Video
and audio applications such as TimPlayer
and Cplay. These apps often provide
better stability and performance
compared to other media players.
CAD Applications
Computer-Aided Designs apps can be
complicated, but Python makes this
simple. Example is Fandango.
Embedded Apps
Python is based on C which means that it
can be used to create Embedded C
software for embedded applications.

| Why Python?
▪ Python is easy to learn
▪ It has a vast community of users
▪ There is plethora of ‘fancy’ career paths for
Python developers
▪ Python can be used for Web development
▪ Python is useful in AI and Machine Learning
▪ Python has millions of modules and frameworks
▪ There has been a lot of adoption and shifting by
Startups and Corporates to Python

| Why Python?
try:
aFile = open('anyOldFile.txt')
myString = aFile.readline()
print('File contents are: ')
print(myString)
except IOError as e:
print "I/O error({0}): {1}".format(e.errno, e.strerror)
#include <iostream>
#include <exception>
using namespace std;
int main () {
int* myarray = NULL;
if (myarray) {
cout << "Not NULL" << endl;
} else {
cout << "Is NULL" << endl;
}
try
{
int* myarray = new int[1000000000];
}
catch (exception& e)
{
cout << "Standard exception: " << e.what() << endl;
if (myarray) {
cout << "Not NULL" << endl;
} else {
cout << "Is NULL" << endl;
}
}
if(myarray) {
cout << "Deleting myarray" << endl;
delete [] myarray;
}
cout << "Returning" << endl;
return 0;
}
Python
C++

3
Variables, Datatypes
(Strings, Int, Float,
List, Tuples, Bool, and
Dictionaries) &
Formatting

| Variables
Variables are containers for storing data values. Unlike other programming languages, Python has no command for declaring a
variable. A variable is created the moment you first assign a value to it.
▪ A variable name must start with a letter or the underscore character
▪ A variable name cannot start with a number
▪ A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
▪ Variable names are case-sensitive (age, Age and AGE are three different variables)
RULES for Naming Variables

| Datatypes
Variables can store data of different types, and different
types can do different things.
Python has the following data types built-in by default, in
these categories:
Text Type: str
Numeric Types: int , float, complex
Sequence Types: list, tuple, range
Mapping Type: dict
Set Types: set, frozenset
Boolean Type: bool
Binary Types: bytes, bytearray, memoryview

| Formatting
String Concatenation
String Methods
String Formatting
There are other string methods
from len() to upper(), to lower().
In fact, you can use the dir(string)
command to get the methods
associated to strings.
There are other string formatting
techniques as well. There’s the %s
method as well as the direct
concatenation approach.

4
Arithmetic Operators,
Comparators, Loops,
& Conditionals

| Arithmetic Operators
Arithmetic Operators
Comparison (Relational) Operators
Assignment Operators
Logical Operators
Bitwise Operators
Membership Operators
Identity Operators
Addition
Subtraction
Multiplication
Division
Modulus
Exponent
Floor Division
==
!=
<>
>
<
>=
<=
=
+=
-=
*=
/=
%=
**=
//=
in
not in
Logical AND
Logical OR
Logical NOT
is
is not

| Loops
Python has two primitive loop commands:
• while loops
• for loops
A loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string). This is less like
the for keyword in other programming languages, and works more like an iterator method as found in other object-orientated
programming languages.
With the for loop we can execute a set of statements, once for each item in a list, tuple, set etc.
for
for
for
With the while loop we can execute a set of statements as long as a condition is true.while

| Conditionals
Python conditionals are used to test if certain conditions or expressions check out. For example, the popular litmus tests of
chemistry. In the test, the paper turns red when the paper is dipped in an acid and blue when dipped in a basic solution. Similarly,
in conditionals, we use the if and else keywords for “action” and “reaction” respectively.if else
You must have noticed the elif keyword; it is not mandatory; you only use it if you have more conditions to test. In other words,
your if/else block would work fine without it.
elif
Read up: Nested Ifs.

5
Functions &
Recursions in
Python

| Functions in Python
A function is a block of code which only runs when it is called. You can pass data, known as parameters, into a function. A
function can return data as a result.
In Python a function is defined using the def keyword:
To let a function return a value, use the return keyword.

| Functions in Python Contd.
Example:
By default, a function must be called with the correct number of arguments. Meaning that if your function expects 2 arguments,
you have to call the function with 2 arguments, not more, and not less.
Give a function all it wants and it would answer your call, otherwise, it spits out errors.

| Recursions
▪ Python also accepts function recursion, which means a defined function can call itself.
▪ Recursion is a common mathematical and programming concept. It means that a function calls
itself. This has the benefit of meaning that you can loop through data to reach a result.
▪ >> The developer should be very careful with recursion as it can be quite easy to slip into writing
a function which never terminates, or one that uses excess amounts of memory or processor
power. However, when written correctly recursion can be a very efficient and mathematically-
elegant approach to programming. We consider and example below:
What does the recursion below do?

| File Handling in Python
File handling is an important part of any web application. Python has several functions for creating, reading, updating, and
deleting files.
We would consider the 4 operations below, i.e, CRUD.
The key function for working with files in Python is the open() function. The open() function takes two parameters;
filename, and mode. Let’s see the syntax below:
Open
To open the file, use the built-in open() function. The open() function returns a file object, which has a read() method for
reading the content of the file:
Read
Note: You can return one line by using the readline() method. Also it is always good practice to close a file when you
are done using it. To do this, use the close method, i.e f.close().

| File Handling in Python Contd.
To write to an existing file, you must add a parameter to the open() function:
"a" - Append - will append to the end of the file | "w" - Write - will overwrite any existing content
Note that new files would be created if they do not already exist.
Write
To delete a file, you must import the OS module, and run its os.remove() function:Delete

| Modules in Python
A module is a Python object with arbitrarily named attributes that you can bind and reference.
Simply, a module is a file consisting of Python code. A module can define functions, classes and variables. A module can also
include runnable code. Modules are all about reusability. Take for example the code below:
Save this code in a file named mymodule.py. To use the module, we use the import statement.
You could wish to import only a function or variable from your module. That wish can be granted without a genie, easily.
You see? Just use from and import!

| Project & Setup Github
Also called “The New Resume”, GitHub is a git repository hosting service.
Simply, Github helps you do version control while coding. Most employer’s
now ask to see your GitHub repository when applying for developer roles.
Setting Up GitHub
▪ Create a GitHub Account
▪ Download and install git from https://git-scm.com/downloads. Choose
your laptop’s specification (OS)
▪ Login in GitHub Username and Password in local machine and start
We would be more exhaustive on this in our demo session. Cheers!
Project:
i. An iPython Notebook has been attached and shared. Study the items in it and work the problem underneath.
ii. Write a recursion for printing a list of first n Fibonacci numbers.
committing changes and pushing files to GitHub!

Thank you for
Listening…
Any Questions?
Contact me on: agbodozie660@gmail.com

First Steps in Python Programming

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