introduction to python.ppt

 General purpose interpreted programming language  Widely used by scientists and programmers of all stripes  Supported by many 3rd-party libraries currently 21,054 on the main python

Guy Griffiths

 General purpose interpreted programming

language

 Widely used by scientists and programmers of all stripes

 Supported by many 3rd-party libraries (currently 21,054 on the main python package website)

 Free!

 Numpy

 Numerical library for python

 Written in C, wrapped by python

 Fast

 Scipy

 Built on top of numpy (i.e Also fast!)

 Common maths, science, engineering routines

 Matplotlib

 Hugely flexible plotting library

 Similar syntax to Matlab

 Produces publication-quality output

 An integrated graphical environment like Matlab (although there are tools which put it in one –

e.g Spyder)

 Specifically designed for

scientists/mathematicians (but the 3rd-party

libraries for plotting/numerical work are some of the best around)

 High performance (but it is very easy to wrap

C/Fortran libraries in Python code)

 Yahoo Maps/Groups

 Google

 NASA

 ESRI

 Linux distros

 Met Office

 Me

 How about several cool things that Python can do?

 Interactive prompt is great for experimenting

 iPython is a fantastic interactive environment

 I mostly write code in iPython interactively, then copy it out into a script when I’m done

 print is easy and intuitive to use

 Yes, you should use a proper debugger, but let’s

face it – print statements are quicker and easier.

 Well, print statements in python are even quicker and easier than that.

 Readable code

 You have to indent all of your loops, conditionals, etc.

 This means that your code will always be indented

in a helpful way

 Inline documentation

 3rd-party libraries

 Numpy, Scipy, Matplotlib are standard libraries for scientific computing

 cf-python is written with meteorologists in mind

 There are 3 rd -party libraries for many, many things

 If you want to do something that isn’t particularly uncommon, there will be a library to do it for you

 No But python can wrap your existing

C/Fortran/R code

 You can get the benefits of a high-level language whilst keeping your fast C/Fortran routines

 This is what Numpy does (and why Numpy is fast)

 and Matlab code translates pretty easily to

python

 A good language to teach

 Questions you won’t hear if you teach python:

▪ “What does ‘Segmentation fault’ mean?”

▪ “Why do I have to click ‘build’ before I run this every

time?”

▪ “Do you know where I can download a license for this so

I can use it at home?”

 Questions you may still hear:

▪ “What’s a variable?”

▪ “Why do we have to do this?”

 Let’s have a look at a few python libraries in action

 Firstly, get version 2.7.x Python 3 is probably more trouble than it’s worth right now.

This is a scientific/engineering oriented distribution of python It includes everything you need to get started

 Linux – it’s already there! Unless you’re running a very unusual distro (in which case you probably already

know what you’re doing).

 Mac – it’s already there on OS X, but it’s old Get a

more up-to-date one [www.python.org]

 The official python tutorial:

http://docs.python.org/tutorial/

 Software Carpentry:

http://software-carpentry.org/

 Dive into Python:

http://www.diveintopython.net/

 Learn Python the Hard Way:

http://learnpythonthehardway.org/

 A Byte of Python:

http://www.ibiblio.org/g2swap/byteofpython/read/

 Python Essential Reference

David M Beazley (Addison Wesley)

 Programming in Python 3: A Complete Introduction to the Python Language

Mark Summerfield (Addison Wesley)

 Learning Python

Mark Lutz (O’Reilly Media)