Introduction to Python Outline Python IS History Installation

Introduction to Python

Outline Python IS ……. History Installation Data Structures Flow of Control Functions Modules References

Python IS …. . Interpreted Like pseudo code, hence development-friendly Intuitive, easy to learn, understandable White-space sensitive; acts as delimiter Portable Extensive standard libraries Compatible with other languages It is OPEN source

History Invented in 1990 by Guido Van Rossum • The name ‘Python’ stems from "Monty Python's Flying Circus“ Currently, he works for Google (since 2005). He wrote a web based code review tool for Google in Python.

Installation Available for FREE online IDLE is a known editor $cmd> python >> print “hello” hello >> import “filename” …. // opens the console

Data Structures Variables - need not be declared String - comes with usual string manipulations “hello” + “ 123” – gives “hello 123” // Concat “Hello”*3 – gives “Hello” // Repetition len(“array_name”) – gives 10 Lists list = [‘a’, ’b’, ’c’] Dynamic array Items can be of any type Indexed based print list[0] // prints ‘a’ Operations such as append(), insert(), pop(), reverse(), sort()

Dictionary Map of keys and values E. g. dictionary = {“key 1: value 1”, “key 2: value 2”, …. . } Operations such as insert, delete, has_key(), keys(), values(), …. Example >> Polygons = {“triangle: 3”, “rectangle: 4”, “pentagon: 5”} >> print Polygons[“triangle”] 3

References Address to the object referred Pointer_a = Pointer_b // doesn’t copy value Both now point to same object >> Pointer_a = [1, 2] >> Pointer_b = Pointer_a >> Pointer_a. append(3) >> print b [1, 2, 3]

Tuples Consists of values separated by commas Nesting allowed E. g. >> tuple = “ 12”, “abc”, 890 >> tuple[0] 12 T = ((“ 1”, “abc”, 1234), (“ 2”, “pqr”, 5678)) Acts like a DB Tuples are immutable x, y, z = T // unpacking Special case for tuple with 0 or 1 items >> empty = () // 0 items >> single = (‘ 123’, ) // trailing comma

Flow of Control (no braces) If (condition): statement 1 statement 2 else: statement 1 while(condition): statement for var in seq: statement // Mark the indentation // Grouping

break Continue Functions def name(arg 1, arg 2, …. ): statement… return // optional Example: def sum(num 1, num 2): return (num 1 + num 2)

Modules/Scripts: File containing statements and functions Comes with “. py” suffix Invoked by “import filename” Object-oriented

References: Python Homepage • http: //www. python. org Python Tutorial • http: //www. python. org/tut Python Documentation • http: //www. python. org/doc