Introduction

• Python is a high-level, popular programming language.
• It was created by Guido van Rossum and first released on February 20, 1991.
• It is used for web and software development, mathematics, data analysis, AI and machine learning
• It works on different platforms and it has simple syntax.
• Due to its simplicity, Python is very productive it can help focus on solving developer's problem
• The most recent version of Python is python3. Python is written in an Integrated Development Environment (IDE), such as Pycharm, VS Code, Spyder, Jupyter, Sublime Text, Thonny. Python was designed for readability and it is therefore simple to use
• In this course we are going to learn everything you need to get started with programming in python

Installation

• Python is available on a variety of platforms, that is Windows, Linux ans MacOS
• Open a terminal window and type "python" to check if it is installed already. This is usually the case in most PC's and if it's not you will have to download python on a web browser
• Go to https://www.python.org/downloads/
• Follow the link to download either for Linux/Unix, Windows or MacOSthe latest version of python
• Make sure to add python to path if you are using windows. Next we need to install a code editor where we write our codes. They are many including Pycharm, Jupyter, VS Code.
• Python files are created using .py file extension ##Python Syntax
• Python uses indentation to indicate a block of code
• Indentation : the spaces at the beginning of a code line ###Example

if 10 > 5:
    print("10 is greater")

• If you skip the indentation you'll get an error

Python Variables

Variables are temporary storage of data in a computer's memory
number = 10

• number is a variable and it is a memory location where the value 10 is stored Variables don't need to be declared with a type Variables are case-sensitive:

X = 'City'
#x and X are different variable names
#X will not overwrite x

Literal - this is a value/data given to a variable

>Example
>> name = 'David'
# David is the literal, the value given to the variable name

Identifier: It is a name used to identify a variable, function, objects or constants
name = 'Becky'
*name* is an identifier
Keyword : This is a reserved word known to the compiler e.g. for, while, in, def

Rules in naming Variables

• A variable name must start with a letter or an underscore
• A variable name cannot start with a number
• Variable names are case-sensitive i.e. case, Case and CASE are different variables
• Keywords should not be used as variables
• Do not use special characters such as ., #, @, -

Python Comments

• These are texts that are ignored during compilation
• Comments are used to explain the code and it makes it more readable
• Comments in python starts with a #.
• To comment multiple lines with #we use Ctrl + /
• Multiple line comments are done by adding triple quotes

"""
this is
a multiline
comment
"""

• """""" """ this is a multiline comment """

Python Data Types

• Variables store data of different data types. Python data types are: Numeric types : int, float, complex

x = 10     #int
x = 10.2   #float
x = 3 + 2j #complex

Sequence types : list, tuple,range

x = ["bus", "car", "cart"] #list
x = ("bus", "car", "cart") #tuple
x = range(3)

Mapping type : dict

x = {"vehicle" : "car",  "name" : "Toyota"}

Set types : set, frozenset

x = {"bus", "car", "cart"}

x = frozenset({"bus", "car", "cart"})

Boolean :bool

x = True
y = False

Text type : str

x = 'Hello World'

Type Conversion

• To get the data type of variable we use the type () function ###Example

name = 'Becky'
print(type(name))
print(name)

Output

 <class 'str'>
 Becky

Getting Input

• We use input () function to receive input from the user ###Example

name = input('What is your name? ') 
print('My name is ' + name)

Output

What is your name? *Becky*
My name is *Becky*

Formatted Strings

• Are useful in situations where you want to dynamically generate some texts with your variables Prefix your string with an 'f' for a formatted string

Example

first = 'Becky'
last = 'Toek'
message = first + '[' + last + '] loves coding' #string concatenation
msg = f'{first} [{last}] loves coding' #formatted string
print(msg)

Output

Becky [Toek] loves coding

Python Operators

• Operators are used to perform operations on variables and values Python has different operators: ## Arithmetic Operators
• Are use with numeric values to perform mathematical operations
• They are:

Assignment Operators

• Assigns values to variables

Logical Operators

• They are used to combine conditional operators

Bitwise Operators

• Used to compare binary values

Comparison Operators

• This operator is used to compare two values
• Colons can be used to align columns.

Identity Operators

Checks for object identity. This is different from equality such that it compares the objects if they are the same objects, with the same memory location

Membership Operators

• Used to test if a sequence is presented in an object

Python Lists

• Lists are used to store multiple items in a variable
  They are created using square brackets

  Example

  vehicles = ["bus", "car", "truck"]
  print(vehicles)

• Lists items have a defined order and it will not change

• Lists allows duplicate values
  i.e.

  mylist = ["apple","mango", "orange", "mango", "kiwi" ]
  print(mylist)

• The items are indexed and the first item has index [0]

• The data type for lists is 'list'.

• Items in a list could contain any data type (int, bool,str,)

  Python Tuples

• Tuples store multiple items in a single variable

• They are written with round brackets()

  Example

  mytuple = ("apple","mango","orange","kiwi")
  print(mytuple)
  

Output

('apple', 'mango', 'orange', 'kiwi')

• Tuple items like lists are ordered, unchangeable and allow duplicate
• The items are indexed and the first item has index [0]
• The data type of tuple is 'tuple'
• Items in a tuple could contain any data type

Python Sets

• Sets are used to store multiple items in a single variable
• They are written with curly brackets {}
• Unlike tuples and lists sets are unordered, unchangeable and do not allow duplicates
• Sets are unindexed
• Sets can be of any data type and they are of the data type sets >Example > > >> myset = {"apple","mango","orange","kiwi"} >> print(myset) > >

Output

{'apple', 'mango', 'orange', 'kiwi'}

Python Dictionaries

• Dictionaries are used store values in key: value pairs
• It is ordered, changeable, and do not allow duplicates
• They are written with curly brackets and have keys and values
• Values in a dictionary can be of any data type
• Dictionaries are defined as objects with data type dict

Example

mydict = {
"food" : "beans",
"type" : "protein",
"amountKg": 2
}
print(mydict)

Output

{'food': 'beans', 'type': 'protein', 'amountKg': 2}