Basics of Python Programming in one PDF File.pdf

Python
▪a programming language that lets you work
quickly and integrate systems more effectively
(Python Software Foundation)
▪created by Guido van Rossum (1990)
▪named after the popular British comedy troupe
Monty Python’s Flying Circus
ECE115.2: Object Oriented Programming for ECE Prepared by: Engr. Ria Marie P. Cordova

Why Python?
▪works on different platforms (Windows, Mac, Linux,
Raspberry Pi, etc.)
▪has a simple syntax
▪runs on an interpreter system
▪can be treated in a procedural way, an object-
oriented way or a functional way

Why Python?
▪has extremely rich libraries
▪has extensive online documentation
▪has multiple programming communities
▪has diverse applications:
✓ web development (server-side)
✓ software development
✓ mathematics
✓ system scripting

Python Input/Output Functions
print()
▪used to generate an output at the console
▪Ex:
print("Hello, Class!")
print(1)

Python Input/Output Functions
input()
▪used to read a line of input entered by the user at
the console and returns it as a string
▪Ex:
num = input("Enter number:")
print(num)

Python Syntax
▪indentation
• refers to the spaces at the beginning of a code line
• very important in Python since it indicates a block
of code
▪ Ex:
if 2 > 1:
print("Two is greater than one.")
if 2 > 1:

Python Syntax
▪indentation
• number of spaces is up to you as a programmer
• the most common use is four, but it has to be at
least one
▪ Ex:
if 2 > 1:
if 2 > 1:

Python Syntax
▪indentation
• the same number of spaces should be used in the
same block of code
▪ Ex:
if 2 > 1:
print("Two is greater than one!")
if 2 > 1:

Python Comments
▪start with a #
▪make code readable
▪completely ignored by the interpreter
▪Ex:
#This is a comment.
print("Hello, Class!") #This is a comment.

Python Comments
▪Multiline Comments
▪Ex:
#Comment1
#Comment2
#Comment3
"""Comment1
Comment2
Comment3"""
Multiline String can also be used
• since Python will ignore string literals
that are not assigned to a variable

Python Variables
▪containers for storing data values
▪Python has no command for declaring a variable
▪a variable is created the moment you first assign a value to it
▪ Ex:
x = 1
y = "Hello"
print(x)
print(y)
assignment operator: =
a, b, c = 9, 2.5, 'Hello'
print(a)
print(b)
print(c)
num1 = num2 = 20
print(num1)
print(num2)

Python Variables
Rules for naming variables
▪must start with a letter or the underscore character
▪cannot start with a number
▪can only contain alpha-numeric characters and underscores (A-
z, 0-9, and _ )
▪are case-sensitive (age, Age and AGE are three different
variables)
▪cannot be any of the Python keywords

Python Variables
▪do not need to be declared with any particular type,
and can even change type after they have been set
▪ Ex:
x = 1 # x is of type int
x = "Hello" # x is now of type str
print(x)

Python Variables
▪Casting
▪ done to specify type of
variable
▪ Ex:
x = str(1) # x will be '1'
y = int(1) # y will be 1
z = float(1) # z will be 1.0
▪type() function
▪ returns the data type of a
variable
▪ Ex:
x = 1
y = "Hello"
print(type(x))
print(type(y))

Python Variables
output variables
x = "A good day"
print(x)
x = "A"
y = "good"
z = "day"
print(x, y, z)
x = "A"
y = "good"
z = "day"
print(x+y+z)
x = 2
y = 9
print(x+y)
x = 2
y = "good"
print(x+y)
x = 2
y = "good"
print(x,y)

Python Variables
Global variables
▪created outside of a function
▪can be used inside and outside of functions
▪Ex:
x = "hi"
def myfunc():
print("Python is " + x)
myfunc()
x = "hi"
def myfunc():
x = "hello"
myfunc()

Python Data Types
Built-in DataTypes
Type
TextType: str
NumericTypes: int, float, complex
SequenceTypes: list, tuple, range
MappingType: dict
SetTypes: set, frozenset
BooleanType: bool
BinaryTypes: bytes, bytearray, memoryview
NoneType: NoneType

Python Data Types
Python Numbers
▪integer (int), floating point number (float), complex
✓ int – whole number (positive/negative)
✓ float – contains decimal (positive/negative); can also be scientific
numbers with an “e” to indicate power of 10
✓ complex – written with a “j” as the imaginary part

Python Data Types
Python Numbers
▪integer (int), floating point number (float), complex
▪ Ex:
x = 1 # int
y1 = 2.9 # float
y2 = 3e4 # float
z = 5j # complex
print(type(x))
print(type(y1))
print(type(y2))
print(type(z))
to verify the data type:

Python Data Types
Python Strings
▪Strings – enclosed by "" or ''
▪ Ex:
x = "Hello" # string
y = 'Hello' # string
x = """Python is a programming
language that lets you work quickly
and integrate systems more
effectively."""
print(x)
Multiline String
• enclosed with three (3) double or
single quotes

Python Data Types
Python Booleans
▪True or False
▪usually used in evaluating expressions
▪ Ex:
print(3>2)
print(3<2)
print(3==2)

Python Data Types
Python Booleans
▪bool() function
▪ evaluates any value to true or false
▪if a value has content, it is evaluated to true (i.e. any string is true except empty string,
any number is true except 0, etc.)
▪empty values, such as (),[],{},"",0,and None, evaluate to false
▪ Ex:
bool("a") #true
bool("1") #true
bool('') #false
bool(None) #false

Python Data Types
Lists
▪used to store multiple items in a single variable
colorList = ["red", "blue", "yellow", "green"]
print(colorList)
✓Items in a list are ordered, changeable, and
allow duplicate values
✓They are indexed (1st item has index [0], the 2nd
item has index [1], and so on)
enclosed with
brackets

Python Data Types
Lists
▪can be of any data type
▪can contain different data types
▪defined as objects with the data type 'list'
list1 = ["red", "blue", "yellow"]
list2 = [1, 3, 5, 7, 9]
list3 = [False, True, False]
list1 = ["Peter", 30, "male", True, "Mary", 29, "female"]

Python Data Types
Lists
▪len() function
▪ determines the number of items in a list
▪ Ex:
colorList = ["red", "blue", "yellow", "green"]
print(len(colorList))

Python Data Types
Lists
▪list() Constructor
▪ can also be used to create a new list
▪ Ex:
colorList = list(("red", "blue", "yellow", "green"))
print(len(colorList))
double
parentheses

Python Data Types
Python Collections (Arrays)
▪4collection data types:
1. List
▪ a collection which is ordered, changeable, and allows duplicate members
2. Tuple
▪ a collection which is ordered, unchangeable, and allows duplicate members.
3. Set
▪ a collection which is unordered, unchangeable (but you can add/remove items), and unindexed.
No duplicate members.
4. Dictionary
▪ a collection which is ordered** and changeable. No duplicate members.

Python Arithmetic Operators
Operator Name Example
+ Addition x+y
- Subtraction x-y
* Multiplication x*y
/ Division x/y
% Modulus x%y
** Exponentiation x**y
// Floor division x//y

Python Comparison Operators
== Equal x == y
!= Not equal x != y
> Greater than x > y
< Less than x < y
>= Greater than or equal to x >= y
<= Less than or equal to x <= y

Python Logical Operators
and returnsTrue if both statements are
true
x < 1 and x < 5
or returnsTrue if one of the statements
is true
x < 4 or x < 8
not reverse the result, returns False if the
result is true
not(x < 3 and x < 6)

Python Identity Operators
is ReturnsTrue if both variables are the
same object
x is y
is not ReturnsTrue if both variables are not
the same object
x is not y

Python Membership Operators
in ReturnsTrue if a value is present in a
sequence
x in y
not in ReturnsTrue if a value is not present
in a sequence
x not in y

Python Bitwise Operators
Operator Name Description Example
& AND Sets each bit to 1 if both bits are 1 x & y
| OR Sets each bit to 1 if one of two bits is 1 x | y
^ XOR Sets each bit to 1 if only one of two bits is 1 x ^ y
~ NOT Inverts all the bits ~x
<< Zero fill left shift Shift left by pushing zeros in from the right
and let the leftmost bits fall off
x << 2
>> Signed right shift Shift right by pushing copies of the leftmost
bit in from the left, and let the rightmost bits
fall off
x >> 2
& AND Sets each bit to 1 if both bits are 1 x & y

Operator
Precedence
Operator Name
() Parentheses
** Exponentiation
+x -x ~x Unary plus, unary minus, and bitwise NOT
* / // % Multiplication, division, floor division, and modulus
+ - Addition and subtraction
<< >> Bitwise left and right shifts
& Bitwise AND
^ Bitwise XOR
| Bitwise OR
==, !=, >, >=, <, <=,
is, is not, in, not in
Comparisons, identity, and membership operators
not Logical NOT
and AND
or OR
If two operators have
the same precedence,
the expression is
evaluated from left
to right.

References:
W3schools (PythonTutorial)
Programiz

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