This document outlines Python as a versatile programming language created by Guido van Rossum in 1991, suitable for a variety of applications including web development, software development, data science, and more. It emphasizes Python's simplicity, readability, and cross-platform capabilities, comparing its syntax to other languages while introducing concepts such as variables, constants, and modules. Key features of Python include easy commenting, assignment operations, and usage of different programming paradigms.

1. Introduction to Python

2. What is Python?
• Python is a popular programming language. It was created by
Guido van Rossum, and released in 1991.
• It is used for:
• web development (server-side),
• software development,
• mathematics,
• system scripting.
• Data Science

3. What Can Python Do?
• Python can be used on a server to create web applications.
• Python can be used alongside software to create workflows.
• Python can connect to database systems. It can also read and
modify files.
• Python can be used to handle big data and perform complex
mathematics.
• Python can be used for rapid prototyping, or for production-ready
software development.

4. Why Python?
• Python works on different platforms (Windows, Mac, Linux,
Raspberry Pi, etc).
• Python has a simple syntax similar to the English language.
• Python has a syntax that allows developers to write programs with
fewer lines than some other programming languages.
• Python runs on an interpreter system, meaning that code can be
executed as soon as it is written. This means that prototyping can be
very quick.
• Python can be treated in a procedural, object-oriented, or
functional way.

5. Python Syntax vs Other programming
Languages
• Python was designed for readability and has some similarities to the
English language with influence from mathematics.
• Python uses new lines to complete a command, as opposed to other
programming languages, which often use semicolons or parentheses.
• Python relies on indentation, using whitespace, to define scope, such
as the scope of loops, functions, and classes. Other programming
languages often use curly brackets for this purpose.

6. Python Syntax
• Python syntax can be executed by writing directly in the Command
Line
• Or by creating a python file on the server, using the .py file extension,
and running it in the Command Line

7. Comments in Python
• Comments are an integral part of any
program
• Single-line comments: indicate what a
section of code does
• Start with # sign
• # This is a comment
7

8. Comments in Python
• Multi-line comments or paragraphs: serve as documentation
• Press the return key after each line, add a new hash mark and continue
your comment
# This is a pretty good example
# of how you can spread comments
# over multiple lines in Python
• Wrap multiple lines comment inside a set of tri
"""
If I really hate pressing `enter` and
typing all those hash marks, I could
just do this instead
"""
8

9. Comments in Python: Practices
• Avoid redundancy: Don’t repeat your self; code
should have little to no redundacy
• # print hello world
print (“ Hello World”)
• Avoid Rude comments
• Use obvious names to variables
9

10. Comments in Python: Practices
• If you spend too much time
explaining what you did, you need
to refactor to make your code
clearer and more concise.
10

11. cosc175/data 11
Variables and Constants
• constant
• alphabetic or numeric value that never changes
during processing
• can be any data type
• can also be used for something that may change
at a later date
• need only be changed in one place
• written in all capital letters and underscores
separating the words.
• PI = 3.14
• MD_TAX_RATE = .06
• variable - value does change during process

12. 12
Identifiers: variable names
• Corresponds to memory location or address
• Naming convention varies from language to language
• a sequence of letters (a-z, A-Z), underscores (_), and digits
(0–9), and must start with a letter or an underscore.
• No spaces in variable names
• any number of characters
• Python is case sensitive
• Cat # cat
• Never use special symbols like !, @, #, $, %, etc.
• Don't start name with a digit.
• meaningful names: hrsWorked, payRate
• Be consistent

13. 13
Assignment operator
=
• Value assigning differs from equality
• variable = expression

14. variable = expression
• variable -physical location in computer memory
• expression
• constant
x = 10;
x = PI;
• another variable to which a value has previously been assigned
y = x;
• a formula to be evaluated
y = a* x /2 + 3;
14

15. 15
assignment
• Processor evaluates the right member of an assignment
statement to get a single value
• it places this value in the memory location (variable
name) given as the left member.
• Not a mathematical equation, can't be switched
stamp = 14 is a valid assignment statement
14 = stamp is not
• The left member of an assignment statement must
always be the name of a computer memory location
(variable name). It cannot be a constant or formula.

16. 16
Assignment Statement What happens in memory
numHours = 10; the value 10 is placed in the memory location
numWidgets
numHours = numHours + 1; numWidget is evaluated. Contains a 10, one is
added to 10, 11 is stored at the memory location
numWidgets
name = "toby" the four characters t-o-b-y are stored in the
memory location name
(note: The single quotes are used as
delimiters and are not stored in memory.)
stuff = numHours; Assuming the value 11 in the memory
location numWidgets, this assignment
statement places the value 11 in stuff
(note: Now both stuff and numWidgets have
the same value.)
hours = numHours * 2 the ALU evaluates the expression on the right
and places the value 30 in the memory
location widget

17. 17
Assignment Statement What happens in memory
numHours = 10; the value 10 is placed in the memory location
numHours
numHours = numHours + 1; numHours is evaluated. Contains a 10, one is
added to 10, 11 is stored at the memory location
numHours
name = "toby" the four characters t-o-b-y are stored in the
memory location name
(note: The single quotes are used as
delimiters and are not stored in memory.)
stuff = numHours; Assuming the value 11 in the memory
location numHours, this assignment
statement places the value 11 in stuff
(note: Now both stuff and numHours have
the same value.)
hours = numHours * 2 the ALU evaluates the expression on the right
and places the value 30 in the memory
location hours

18. Assignment Operators
18

19. cosc175/operators 19
Modules in Python
• Module: A module is a file containing Python code that can
be used by other modules or scripts.
• A module is made available for use via the import
statement.
• Once a module is imported, any object defined in that
module can be accessed using dot notation.
• import math
• math.pow(2, 4)

20. 20
Relational Operators
op operation
< Less than
<= Less than or equal to
> Greater than
>= Greater than or equal to
== Equal to
!= Not equal to
<> Different from

21. 21
Logical Operators