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% Tutorial slides on Python.

%

% Author: Prabhu Ramachandran <prabhu at aero.iitb.ac.in>

% Copyright (c) 2005-2008, Prabhu Ramachandran

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% Taken from Fernando's slides.

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\usepackage{listings}

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% Title page

\title[Basic Python]{Python:\\A great programming toolkit}

\author[Asokan \& Prabhu] {Asokan Pichai\\Prabhu Ramachandran}

\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}

\date[] {10, August 2009}

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%% Delete this, if you do not want the table of contents to pop up at

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  \begin{frame}<beamer>

    \frametitle{Outline}

    \tableofcontents[currentsection,currentsubsection]

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% DOCUMENT STARTS

\begin{document}

\begin{frame}

  \titlepage

\end{frame}

\begin{frame}

  {Acknowledgements}

  \begin{center}

  This program is conducted by\\

  IIT, Bombay\\

  through CDEEP\\as part of  the open source initiatives\\

  under the aegis of\\

  \alert{National Mission on Education through ICT,} \\

  Ministry of HRD.

  \end{center}

\end{frame}

\begin{frame}

  \frametitle{Outline}

  \tableofcontents

  % You might wish to add the option [pausesections]

\end{frame}

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% TODO

%

%  * Add slide on Python packages (modules)

%  * Add slides on reference counting.

\section{Agenda}

\begin{frame}{About the Workshop}

  \begin{description}

	\item[Day 1, Session 1] Sat 09:30--11:00

	\item[Day 1, Session 2] Sat 11:15--12:45

	\item[Day 1, Session 3] Sat 13:45--15:15

	\item[Day 1, Session 4] Sat 15:30--17:00

        \item[Day 2, Session 1] Sun 09:30--11:00

	\item[Day 2, Session 2] Sun 11:15--12:45

	\item[Day 2, Session 3] Sun 13:45--15:15

	\item[Day 2, Session 4] Sun 15:30--17:00

  \end{description}

\end{frame}

\section{Agenda}

\begin{frame}{About the Workshop}

  \begin{block}{Goal of the workshop}

  \end{block}

\end{frame}

\begin{frame}{Checklist}

\end{frame}

\section{Overview}

\begin{frame}{Session 1}

  \begin{itemize}

	\item Introduction and motivation

	\item Using the interpreter(s)

	\item Basic data types: int, float, string

	\item Basic data structures: list

	\item Basic console IO: \texttt{raw\_input(), print}

    \item Basic control flow: \texttt{if, while}

	\item Problem set 1

    \item Functions $\rightarrow$ Problem set 2

    \item lists, \texttt{for}  $\rightarrow$ Problem set 3

    \item IO, Modules $\rightarrow$ Problem sets 4,5, \ldots

  \end{itemize}

\end{frame}

\begin{frame}

  \frametitle{Introduction}

  \begin{itemize}

  \item Creator and BDFL: Guido van Rossum

  \item ``Python'' as in Monty Python's Flying Circus

  \item PSF license (like BSD: no strings attached)

  \item Highly cross platform

  \item \alert{Philosophy:} Simple and complete by design

  \end{itemize}

\end{frame}

\begin{frame}

  \frametitle{Resources}

  \begin{itemize}

  \item Part of many GNU/Linux distributions

  \item Web: \url{http://www.python.org}

  \item Doc: \url{http://www.python.org/doc}

  \item Free Tutorials:

    \begin{itemize}

    \item Official Python tutorial: \url{http://docs.python.org/tut/tut.html}

    \item Byte of Python: \url{http://www.byteofpython.info/}

    \item Dive into Python: \url{http://diveintopython.org/}

    \end{itemize}

  \end{itemize}

\end{frame}

\begin{frame}

  \frametitle{Why Python?}

  \begin{itemize}

  \item High level, interpreted, modular, OO

  \item Much faster development cycle

  \item Powerful interactive environment

  \item Rapid application development

  \item Rich standard library and modules

  \item Interfaces well with C++, C and FORTRAN

  \item \alert{More than a math package $\Rightarrow$ some extra work compared to math packages}

  \end{itemize}

\end{frame}

\begin{frame}

  \frametitle{Use cases}

  \begin{itemize}

  \item NASA: Space Shuttle Mission Design

  \item AstraZeneca: Collaborative Drug Discovery

  \item ForecastWatch.com: Helps Meteorologists

  \item Industrial Light \& Magic: Runs on Python

  \item Zope: Commercial grade Toolkit

  \item Plone: Professional high feature CMS

  \item RedHat: install scripts, sys-admin tools

  \item Django: A great web application framework

  \item Google: A strong python shop

  \end{itemize}

\end{frame}

\begin{frame}

  \frametitle{To sum up, python is\ldots}

  \begin{itemize}

  \item dynamically typed, interpreted $\rightarrow$ rapid testing/prototyping

  \item powerful, very high level

  \item has full introspection 

  \item Did we mention powerful?

  \end{itemize}

  \begin{block}{But \ldots}

    may be wanting in performance. specialised resources such as SWIG, \alert{Cython} are available 

  \end{block}

  \inctime{15}

\end{frame}

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\section{Python}

\subsection{Getting Started}

\begin{frame}[fragile]{At the prompt, type the following}

   \begin{lstlisting}

>>> print 'Hello Python' 

>>> print 3124 * 126789

>>> 1786 % 12

>>> 3124 * 126789

>>> a = 3124 * 126789

>>> big = 12345678901234567890 ** 3

>>> verybig = big * big * big * big 

>>> 12345**6, 12345**67, 12345**678

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]{At the prompt, type the following}

   \begin{lstlisting}

>>> s = 'Hello '

>>> p = 'World'

>>> s + p 

>>> s * 12 

>>> s * s

>>> s + p * 12, (s + p)* 12

>>> s * 12 + p * 12

>>> 12 * s 

    \end{lstlisting}

\end{frame}

\begin{frame}[fragile]{At the prompt, type the following}

  \begin{lstlisting}

>>> 17/2

>>> 17/2.0

>>> 17.0/2

>>> 17.0/8.5

>>> int(17/2.0)

>>> float(17/2)

>>> str(17/2.0)

>>> round( 7.5 )

  \end{lstlisting}

  \begin{block}{Mini exercise}

	Round a float to the nearest integer, using \texttt{int()}?

  \end{block}

\end{frame}

\begin{frame}{Midi exercises}

  \begin{center}

    \begin{itemize}

      \item What does this do?

      \item \texttt{round(amount * 10) /10.0 }

    \end{itemize}

  \end{center}

\end{frame}

\begin{frame}{More exercises?}

  \begin{center}

    \begin{block}{Round sums}

      How to round a number to the nearest  5 paise?\\

      \begin{description}

        \item[Remember] 17.23 $\rightarrow$ 17.25,\\ while 17.22 $\rightarrow$ 17.20\\

      \end{description}

      How to round a number to the nearest 20 paise?

    \end{block}

  \end{center}

\end{frame}

\begin{frame}[fragile] {A question of good style}

  \begin{lstlisting}

    amount = 12.68

    denom = 0.05

    nCoins = round(amount/denom)

    rAmount = nCoins * denom

  \end{lstlisting}

  \pause

  \begin{block}{Style Rule \#1}

    Naming is 80\% of programming

  \end{block}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Odds and ends}

  \begin{itemize}

    \item Case sensitive

    \item Dynamically typed $\Rightarrow$ need not specify a type

      \begin{lstlisting}

a = 1

a = 1.1

a = "Now I am a string!"

      \end{lstlisting}

    \item Comments:

      \begin{lstlisting}

a = 1  # In-line comments

# Comment in a line to itself.

a = "# This is not a comment!"

      \end{lstlisting}

  \end{itemize}

  \inctime{15}

\end{frame}

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\subsection{Data types}

\begin{frame}

  \frametitle{Basic types}

  \begin{itemize}

  \end{itemize}

  \begin{block}{Also to be discussed later}

    tuples, lists, dictionaries, functions, objects\ldots

  \end{block}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Numbers}

  \vspace*{-0.25in}

  \begin{lstlisting}

>>> a = 1 # Int.

>>> l = 1000000L # Long

>>> e = 1.01325e5 # float

>>> f = 3.14159 # float

>>> c = 1+1j # Complex!

>>> print f*c/a

(3.14159+3.14159j)

>>> print c.real, c.imag

1.0 1.0

>>> abs(c)

1.4142135623730951

>>> abs( 8 - 9.5 )

1.5

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Boolean}

  \begin{lstlisting}

>>> t = True

>>> f = not t

False

>>> f or t

True

>>> f and t

False

  \end{lstlisting}

  \begin{block}{Try:}

  NOT True\\

  not TRUE

  \end{block}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Relational and logical operators}

  \begin{lstlisting}

>>> a, b, c = -1, 0, 1

>>> a == b

False

>>> a <= b 

True

>>> a + b != c

True

>>> a < b < c

True

>>> c >= a + b

True

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Strings}

  \begin{lstlisting}

s = 'this is a string'

s = 'This one has "quotes" inside!'

s = "I have 'single-quotes' inside!"

l = "A string spanning many lines\

one more line\

yet another"

t = """A triple quoted string does

not need to be escaped at the end and 

"can have nested quotes" etc."""

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{More Strings}

  \vspace*{-0.2in}

  \begin{lstlisting}

>>> w = "hello"    

>>> print w[0] + w[2] + w[-1]

hlo

>>> len(w) # guess what

5

>>> s = u'Unicode strings!'

>>> # Raw strings (note the leading 'r')

... r_s = r'A string $\alpha \nu$'

  \end{lstlisting}

\pause

  \begin{lstlisting}

>>> w[0] = 'H' # Can't do that!

Traceback (most recent call last):

  File "<stdin>", line 1, in ?

TypeError: object does not support item assignment

  \end{lstlisting}

\end{frame}

\begin{frame}

  \frametitle{Let us switch to IPython}

  Why?

  \begin{block}

    {Better help (and a lot more)}

    Tab completion\\

    ?\\

    .?\\

    object.function?

  \end{block}

\end{frame}

\begin{frame}[fragile]

  \frametitle{More on strings}

  \begin{lstlisting}

In [1]: a = 'hello world'

In [2]: a.startswith('hell')

Out[2]: True

In [3]: a.endswith('ld')

Out[3]: True

In [4]: a.upper()

Out[4]: 'HELLO WORLD'

In [5]: a.upper().lower()

Out[5]: 'hello world'

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]{Still with strings}

  \begin{lstlisting}

In [6]: a.split()

Out[6]: ['hello', 'world']

In [7]: ''.join(['a', 'b', 'c'])

Out[7]: 'abc'

In [8] 'd' in ''.join( 'a', 'b', 'c')

Out[8]: False

  \end{lstlisting}

  \begin{block}{Try:}

    \texttt{a.split( 'o' )}\\

    \texttt{'x'.join( a.split( 'o' ) )}

  \end{block}

\end{frame}

\begin{frame}[fragile]{Surprise! strings!!}

  \begin{lstlisting}

In [11]: x, y = 1, 1.2

In [12]: 'x is %s, y is %s' %(x, y)