Introduction to Python Programming

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Google (Youtube)
Facebook (Tornado)
Dropbox
Yahoo
NASA
IBM
Mozilla
Quora
Instagram (Django)
Reddit

Search algorithms
Log analysis
Google Data Python Client Library
Google APIs Client Library for Python
Google AdWords API Python Client Library
Machine Learning
Robotics projects

NAME IS BASED ON A BBC
COMEDY SERIES FROM THE 1970S
Monty Python's Flying Circus
Guido van Ro s s u m
December 1989

Python is used across domains such as:
Scripting
Testing
Web Development
IoT Programming
Data Science

Programming is error-prone!
Programming errors are called bugs
The process of tracking them down is called debugging

Easy-to-learn:
Python has few keywords, a simple structure, and a clearly defined syntax.
Easy-to-read:
Python code is more clearly defined and visible to the eyes.
Easy-to-maintain:
Python's source code is fairly easy to maintain.
A broad standard library:
Python's bulk of the library is very portable and cross-platform compatible on
UNIX, Windows, and Macintosh.
Interactive Mode:
Python has support for an interactive mode that allows interactive testing and
debugging of snippets of code.
Portable:
Python can run on a wide variety of hardware platforms and has the same
interface on all platforms.

Extendable:
You can add low-level modules to the Python interpreter. These modules
enable programmers to add to or customize their tools to be more efficient.
Databases:
Python provides interfaces to all major commercial databases.
GUI Programming:
Python supports GUI applications that can be created and ported to many
system calls, libraries, and windows systems, such as Windows MFC,
Macintosh, and the X Window system of Unix.
Scalable:
Python provides a better structure and support for large programs than shell
scripting.

Portability:
A property of a program that can run on more than one kind of
computer.
Interpret:
To execute a program in a high-level language by translating it one
line at a time.
Compile:
To translate a program written in a high-level language into a low-level
language all at once, in preparation for later execution.

A program is a sequence of instructions that specifies how to
perform a computation.
Input: Get data from the keyboard, a file, or some other device.
Output: Display data on the screen or send data to a file or other
device.
Process:
1.Math: Perform basic mathematical operations like addition
and multiplication.
2.Conditional execution: Check for certain conditions andexecute
the appropriate code.
3.Repetition: Perform some action repeatedly, usually with some
variation.

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Num bers
1.int (signed integers):
They are often called just integers or int, are positive or negative whole numbers
with no decimal point.
2. long (long integers ):
Also called long, they are integers of unlimited size, written like integers and
followed by an uppercase or lowercaseL.
3. float (floating point real values):
Also called floats, they represent real numbers and are written with a decimal
point dividing the integer and fractional parts. Floats may also be in scientific
notation, with Eor e indicating the power of 10 (2.5e2 = 2.5 x 102= 250).
4. complex (complex numbers):
Are of the form a + bJ, where a and b are floats and J (or j) represents the square
root of -1 (which is an imaginary number). The real part of the number is a, and the
imaginary part is b.

1.Variables are reserved memory locations that are used to store values and
are referenced by a name.
Example: Assigning a contact number and referencing it by a contact name
2.Syntax to define a variable is asfollows:
variableName = value
Example: phoneNumber = 12345

Variable name should start with an alphabet orunderscore (‘_’) followed
by any number of alphabets, digits andunderscores
Variable names are case sensitive.
Example: phoneNumber is different from PhoneNumber and phonenumber
Variable name cannot be a reserved name
Example: print, if, for, etc
Variable name cannot contain any special character other thanunderscore

List , List comprehension
Tuple
Dictionary

Syntax error
Semantic Error
Runtime Error

While loop – syntax-while(condition):
For loop – syntax – for i in range(0,n):

A collection of built-in modules, each providing different functionality
beyond what is included in the corePython.
import math
math.sqrt(16)
math.factorial(10)
These are called as fruitful functions in python.

Functions are created to make calculations easy toreuse
The general form of a function call is <<function_name>>(<<arguments>>)
An argument is an expression that appears between the parenthesis of a
function call.
The number within parenthesis in the below function call is argument.

Rules to execute a function call:
Evaluate each argument one at a time, working from left to right.
Pass the resulting values into the function.
Executes the function.
The result is obtained.
abs(-7) + abs (3)
pow(abs(-2), round(3.2))

X = input(“Enter an expression:”)
Multiple assignments are also possible
Ex: x,y = 3,4
x,y = map(int, input().split())

def f1():
•print(‘Inside the function’)
f1()

def f1(number):
•print(number)
F1(5)

def add():
print(“Enter 2 numbers to add:”)
a =int(input(“1st number:”))
b =int(input(“2nd number:”))
return(a+b)
result = add()
print(‘After addition:’ result)

num=int(input("Enter the number"))
fact=1
for i in range (1,num+1):
fact=fact*i
print(fact)

def fact(num):
fact=1
for i in range (1,num+1):
fact=fact*i
print(fact)
return fact
fact(num)

def fact(num):
if(num==1):
return(1
)
else:
return num*fact(num-1)
print(fact(num))

Strings are a collection of characters. They are enclosed in
single or double-quotes.
Eg: ‘Climate is pleasant’
‘1234’
‘#@$’

Operators overloading are available in default.
3*’a’ = ‘aaa’
‘a’+’a’ = ‘aa’
‘a’ +3 will give synatax error (you cannot add a string anda number)
‘a’ +‘3’ = ‘a3’
‘a’*’a’ will give a syntax error.

Indexing is used to extract individual characters from astring
Indexing in python starts from 0.
S =‘welcome’
S[0] = ‘w’
S[1]=‘e’ ….

Slicing is taking subsets from a string.
Lower limit is inclusive where as Upper limit isexclusive.
S=‘welcome’
S[0:2] ??
S[0:] ??
S[:3] ??
S[:] ???
S[0:4]??

‘a’ in ‘ssn’
‘ss’ in ‘ssn’
Replacing a string:
Text =‘Python is easy’
Text =Text.replace(‘easy’ , ‘easy and powerful’)

Explore the other functions -Assignment

Write a python function to find the max of 3 numbers
Check whether a number is palindrome using function
Check whether a string is palindrome using function

Write a Python function that accepts a string and calculatethe
number of upper case letters and lower case letters

Introduction to Python Programming

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