%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%Tutorial slides on Python.

%

% Author: FOSSEE 

% Copyright (c) 2009, FOSSEE, IIT Bombay

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\documentclass[14pt,compress]{beamer}

%\documentclass[draft]{beamer}

%\documentclass[compress,handout]{beamer}

%\usepackage{pgfpages} 

%\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]

% Modified from: generic-ornate-15min-45min.de.tex

\mode<presentation>

{

  \usetheme{Warsaw}

  \useoutertheme{infolines}

  \setbeamercovered{transparent}

}

\usepackage[english]{babel}

\usepackage[latin1]{inputenc}

%\usepackage{times}

\usepackage[T1]{fontenc}

% Taken from Fernando's slides.

\usepackage{ae,aecompl}

\usepackage{mathpazo,courier,euler}

\usepackage[scaled=.95]{helvet}

\definecolor{darkgreen}{rgb}{0,0.5,0}

\usepackage{listings}

\lstset{language=Python,

    basicstyle=\ttfamily\bfseries,

    commentstyle=\color{red}\itshape,

  stringstyle=\color{darkgreen},

  showstringspaces=false,

  keywordstyle=\color{blue}\bfseries}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Macros

\setbeamercolor{emphbar}{bg=blue!20, fg=black}

\newcommand{\emphbar}[1]

{\begin{beamercolorbox}[rounded=true]{emphbar} 

      {#1}

 \end{beamercolorbox}

}

\newcounter{time}

\setcounter{time}{0}

\newcommand{\inctime}[1]{\addtocounter{time}{#1}{\tiny \thetime\ m}}

\newcommand{\typ}[1]{\lstinline{#1}}

\newcommand{\kwrd}[1]{ \texttt{\textbf{\color{blue}{#1}}}  }

%%% This is from Fernando's setup.

% \usepackage{color}

% \definecolor{orange}{cmyk}{0,0.4,0.8,0.2}

% % Use and configure listings package for nicely formatted code

% \usepackage{listings}

% \lstset{

%    language=Python,

%    basicstyle=\small\ttfamily,

%    commentstyle=\ttfamily\color{blue},

%    stringstyle=\ttfamily\color{orange},

%    showstringspaces=false,

%    breaklines=true,

%    postbreak = \space\dots

% }

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Title page

\title[Basic Python]{Python language: Functions, modules and objects}

\author[FOSSEE Team] {The FOSSEE Group}

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

\date[] {1 May, 2010\\Day 2, Session 3}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}

%\logo{\pgfuseimage{iitmlogo}}

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

%% the beginning of each subsection:

\AtBeginSubsection[]

{

  \begin{frame}<beamer>

    \frametitle{Outline}

    \tableofcontents[currentsection,currentsubsection]

  \end{frame}

}

\AtBeginSection[]

{

  \begin{frame}<beamer>

    \frametitle{Outline}

    \tableofcontents[currentsection,currentsubsection]

  \end{frame}

}

% If you wish to uncover everything in a step-wise fashion, uncomment

% the following command: 

%\beamerdefaultoverlayspecification{<+->}

%\includeonlyframes{current,current1,current2,current3,current4,current5,current6}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% DOCUMENT STARTS

\begin{document}

\begin{frame}

  \titlepage

\end{frame}

\begin{frame}

  \frametitle{Outline}

  \tableofcontents

  % You might wish to add the option [pausesections]

\end{frame}

\section{Functions}

\subsection{Default arguments}

\begin{frame}[fragile]

  \frametitle{Functions: default arguments}

  \begin{lstlisting}

In []: greet = 'hello world'

In []: greet.split()

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

In []: line = 'Rossum, Guido, 54, 46, 55'

In []: line.split(',')

Out[]: ['Rossum', ' Guido', ' 54',

                        ' 46', ' 55']

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Functions: default arguments \ldots}

  \begin{lstlisting}

In []: def welcome(greet, name="World"):

  ....     print greet, name

In []: welcome("Hello")

Hello World

In []: welcome("Hi", "Guido")

Hi Guido

  \end{lstlisting}

\end{frame} 

\subsection{Keyword arguments}

\begin{frame}[fragile]

  \frametitle{Functions: Keyword arguments}

We have seen the following

\begin{lstlisting}

legend(['sin(2y)'], loc = 'center')

plot(y, sin(y), 'g', linewidth = 2)

annotate('local max', xy = (1.5, 1))

pie(science.values(), 

            labels = science.keys())

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Functions: keyword arguments \ldots}

  \begin{lstlisting}

In []: def welcome(greet, name="World"):

  ....     print greet, name

In []: welcome("Hello", "James")

Hello James

In []: welcome("Hi", name="Guido")

Hi Guido

In []: welcome(name="Guido", greet="Hey")

Hey Guido

  \end{lstlisting}

\end{frame}

\subsection{Built-in functions}

\begin{frame}

  {Before writing a function}

  \begin{itemize}

      \item Variety of built-in functions are available

      \item \typ{abs, any, all, len, max, min}

      \item \typ{pow, range, sum, type}

      \item Refer here:

          \url{http://docs.python.org/library/functions.html}

  \end{itemize}

  \inctime{10} 

\end{frame}

\subsection{Exercises}

\begin{frame}{Problem set 3: Problem 3.1}

  Write a function to return the gcd of two numbers.

\end{frame}

\begin{frame}{Problem 3.2}

Write a program to print all primitive pythagorean triads (a, b, c) where a, b are in the range 1---100 \\

A pythagorean triad $(a,b,c)$ has the property $a^2 + b^2 = c^2$.\\By primitive we mean triads that do not `depend' on others. For example, (4,3,5) is a variant of (3,4,5) and hence is not primitive. And (10,24,26) is easily derived from (5,12,13) and is also not primitive.

\end{frame}

\begin{frame}{Problem 3.3}

  Write a program that generates a list of all four digit numbers that have all their digits even and are perfect squares.\newline\\\emph{For example, the output should include 6400 but not 8100 (one digit is odd) or 4248 (not a perfect square).}

\inctime{15}

\end{frame}

\section{Modules}

\begin{frame}[fragile]

  \frametitle{\texttt{from} \ldots \texttt{import} magic}

  \begin{lstlisting}

from scipy.integrate import odeint

from scipy.optimize import fsolve

  \end{lstlisting}

\emphbar{Above statements import a function to our namespace}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Running scripts from command line}

  \small

  \begin{itemize}

    \item Fire up a terminal

    \item python four\_plot.py

  \end{itemize}

  \pause

  \begin{lstlisting}

Traceback (most recent call last):

  File "four_plot.py", line 1, in <module>

    x = linspace(-5*pi, 5*pi, 500)

NameError: name 'linspace' is not defined

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Remedy \ldots}

  \begin{lstlisting}

from scipy import *

  \end{lstlisting}

\alert{Now run python four\_plot.py again}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Now what?}

  \begin{lstlisting}

Traceback (most recent call last):

  File "four_plot.py", line 1, in <module>

    x = plot(x, x, 'b')

NameError: name 'plot' is not defined

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Remedy \ldots}

  \begin{lstlisting}

from pylab import *

  \end{lstlisting}

\alert{Now run python four\_plot.py again!!}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Modules}

  \begin{itemize}

    \item The \kwrd{import} keyword ``loads'' a module

    \item One can also use:

      \begin{lstlisting}

In []: from scipy import *

In []: from scipy import linspace

      \end{lstlisting}    

    \item What is the difference?

    \item \alert{Use the former only in interactive mode}

    \end{itemize}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Package hierarchies}

  \begin{lstlisting}

from scipy.integrate import odeint

from scipy.optimize import fsolve

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{\texttt{from} \ldots \texttt{import} - conventional way!}

  \small

  \begin{lstlisting}

from scipy import linspace, pi, sin

from pylab import plot, legend, annotate

from pylab import xlim, ylim

x = linspace(-5*pi, 5*pi, 500)

plot(x, x, 'b')

plot(x, -x, 'b')

plot(x, sin(x), 'g', linewidth=2)

plot(x, x*sin(x), 'r', linewidth=3)

legend(['x', '-x', 'sin(x)', 'xsin(x)'])

annotate('origin', xy = (0, 0))

xlim(-5*pi, 5*pi)

ylim(-5*pi, 5*pi)

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{\texttt{from} \ldots \texttt{import} - conventional way!}

  \small

  \begin{lstlisting}

import scipy

import pylab

x = scipy.linspace(-5*scipy.pi, 5*scipy.pi, 500)

pylab.plot(x, x, 'b')

pylab.plot(x, -x, 'b')

pylab.plot(x, scipy.sin(x), 'g', linewidth=2)

pylab.plot(x, x*scipy.sin(x), 'r', linewidth=3)

pylab.legend(['x', '-x', 'sin(x)', 'xsin(x)'])

pylab.annotate('origin', xy = (0, 0))

pylab.xlim(-5*scipy.pi, 5*scipy.pi)

pylab.ylim(-5*scipy.pi, 5*scipy.pi)

  \end{lstlisting}

\end{frame}

\begin{frame}

  \frametitle{Modules: Standard library}

  \begin{itemize}

  \item Very powerful, ``Batteries included''

  \item Some standard modules:

    \begin{itemize}

    \item Math: \typ{math}, \typ{random}

    \item Internet access: \typ{urllib2}, \typ{smtplib}

    \item System, Command line arguments: \typ{sys}

    \item Operating system interface: \typ{os}

    \item Regular expressions: \typ{re}

    \item Compression: \typ{gzip}, \typ{zipfile}, and \typ{tarfile}

    \item And a whole lot more!

    \end{itemize}

  \item Check out the Python Library reference:

    \url{http://docs.python.org/library/}

  \end{itemize}

\inctime{5}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Modules of special interest}

  \begin{description}[matplotlibfor2d]

    \item[\texttt{pylab}] Easy, interactive, 2D plotting

    \item[\texttt{scipy}] arrays, statistics, optimization, integration, linear

            algebra, Fourier transforms, signal and image processing,

            genetic algorithms, ODE solvers, special functions, and more

    \item[\texttt{Mayavi}] Easy, interactive, 3D plotting

  \end{description}

\end{frame}

\section{Objects}

\begin{frame}{Everything is an Object!}

  \begin{itemize}

    \item \typ{int}

    \item \typ{float}

    \item \typ{str}

    \item \typ{list}

    \item \typ{tuple}

    \item \typ{string}

    \item \typ{dictionary}

    \item \typ{function}

    \item User defined class is also an object!

  \end{itemize}

\end {frame}

\begin{frame}[fragile]

\frametitle{Using Objects}

  \begin{itemize}

    \item Creating Objects

    \begin{itemize}

      \item Initialization

    \end{itemize}

    \begin{lstlisting}

In []: a = str()

In []: b = "Hello World"

    \end{lstlisting}

    \item Object Manipulation

    \begin{itemize}

      \item Object methods

      \item ``.'' operator

    \end{itemize}

  \begin{lstlisting}

In []: "Hello World".split()

Out[]: ['Hello', 'World']

    \end{lstlisting}

  \end{itemize}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Objects provide consistency}

  \small

  \begin{lstlisting}

for element in (1, 2, 3):

    print element

for key in {'one':1, 'two':2}:

    print key

for char in "123":

    print char

for line in open("myfile.txt"):

    print line

for line in urllib2.urlopen('http://site.com'):

    print line

  \end{lstlisting}

  \inctime{10}

\end{frame}

\begin{frame}

  \frametitle{What did we learn?}

  \begin{itemize}

    \item Functions: Default and Keyword arguments

    \item Modules

    \item Objects

  \end{itemize}

\end{frame}

\end{document}

%% Questions for Quiz %%

%% ------------------ %%

\begin{frame}

    \frametitle{\incqno}

  How many items can a function return?

\end{frame}