BITS PilaniPilani Campus

Dhanashree N P

Lecturer (Off-Campus) Computer Science

 'Hello, World!' with Python

04-01-2017

DISCLAIMER

This is NOT a Python programming tutorial!!

Session Overview

1. The clichéd title 2. Python & PSF3. Features of Python4. Success stories: using Python5. Sample programs 6. FAQs7. Python programs are ‘slow’ – Myth?8. Why is Python preferred by many?9. Reference Links

The clichéd titleAny programming tutorial starts with a ‘Hello, World!’ program. Let’s use the same to answer ‘Why Python?’

Python & PSF

• “hobby” programming project

• Interpreter for a scripting language

Dec 1989

• Python 2.0 – 16th Oct• Unicode Support, cycle-

detecting GC

Oct 2000• Python 3.0• Backward-Incompatible• Features backported to

backward compatible 2.7.x, 2.6.x

Dec 2008

Guido van Rossum – creator of Python – benevolent dictator for life (BDFL)

Python Software Foundation(PSF) - manages the open-source licensing for Python 2.1 and later - mission is to promote, protect and advance Python; support

and facilitate growth of international & diverse community of Python programmers. [2001]

Python: Features

6

Language Features

High-level

General Purpose

Multi-Paradigm

Interpreted

Fully Supported

• Object-oriented Programming• Structured Programming

Supported by Language

Features

• Functional Programming• Aspect Oriented Programming

Supported by

Extensions

• Design by Contract• Logic Programming

Python: Features

7

Features

Dynamic typing

Late binding

ExtensibleWhite Spaces

Automatic Memory

Management

The name Python was inspired from the series Monty Python’s Flying Circus

a = 3a = “a string”a = [‘a’, ‘list’]len(a)

Success Stories using Python

8

Web & Analysis• Mozilla• Google• Youtube• Bitly• ForecastWatch.co

m etc

Science, Energy• ExpEYES [portable

scientific laboratory]• VAMPZero [aircraft

conceptual design]• Eco Mode @ SMS

Siemag AG• Large Hadron Collider

(CERN)• EPRI (Life on Mars - ESA)

[Python powered clusters and graphics processing]

Animation & Graphics• Blender• Houdini

Systems Cloud, Data Centers etc.• Open Stack• Google App

Engine• Flying Circus• rackspace

Others• Scientific &

Numeric Processing – SciPy, NumPy

• Machine Learning & Analytics – SocialCorps, Innoplexus, Fractal Analysis

• Automation of applications [ Jython]Oracle in ODI

A few lines of code..

9Examples shown use Python 2.7.12

A simple word-count program – Python shell/command line

A simple word-count program using the os module – Python shell/command line

A few more lines of code..

10Examples shown use Python 2.7.12

Code to check the word count limit for multiple files

Save this code in a file as pgm.pyFrom the command line (Linux) – execute it using: python pgm.pyOr from within IDLE shell - execfile('pgm.py')

A few FAQs

11

1. What version to choose – 2.7.x or 3.x? https://wiki.python.org/moin/Python2orPython3

2. What to use for development?1. Any text editor (from notepad to Sublime Text)2. IDE (Eric, Pycharm) 3. Online Web Application: Jupyter (iPython)

3. How to run?1. Use the command line python filename [arguments]2. Use the Python shell execfile(filename[,arguments])

4. How to debug? pdb module https://docs.python.org/2/library/pdb.html

Is Python ‘slow’ ? Why?

12

Yes – most of the raw code is slower than C/C++. But it is faster than Ruby/JavaScript [Source: Internet]

A few reasons are:1. Dynamic v/s Static typing2. Interpreted v/s Compiled3. Inefficient memory access due to its object model (list

access)

But there are hacks to overcome these: vectorised operations [SciPy, NumPy etc.], calling compiled code, using specific libraries etc.

Read more at: https://jakevdp.github.io/blog/2014/05/09/why-python-is-slow/

Why not something else?

Source: https://www.python.org/about/

BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956

Questions?

Source: https://www.explainxkcd.com/wiki/index.php/353:_Python

BITS Pilani, Pilani Campus

Python – About, Documentation, Downloads etc. - https://www.python.org/Python Software Foundation - https://www.python.org/psf/Logos and Usage - https://www.python.org/community/logos/History and Timelines -

https://en.wikipedia.org/wiki/Python_(programming_language)Some Success Stories and Case studies -

http://brochure.getpython.info/media/releases/psf-python-brochure-vol.-i-final-download.pdf/at_download/file

Some Tutorials/Books to start with: The Python Tutorial https://docs.python.org/3/tutorial/

LearnPython.org http://www.learnpython.org/Think Python: How to Think Like a Computer Scientist – Allen. B. Downey http://www.greenteapress.com/thinkpython/html/Python Playground: Geeky Projects for the curious Programmer – Mahesh Venkitachalam https://www.nostarch.com/pythonplayground

Reference Links

BITS Pilani, Deemed to be University under Section 3 of UGC Act, 195617

Thank You!