2 % Tutorial slides on Python.

     2 %Tutorial slides on Python.

     4 % Author: Prabhu Ramachandran <prabhu at aero.iitb.ac.in>

     4 % Author: FOSSEE 

     5 % Copyright (c) 2005-2009, Prabhu Ramachandran

     5 % Copyright (c) 2009, FOSSEE, IIT Bombay

     8 \documentclass[compress,14pt]{beamer}

     8 \documentclass[14pt,compress]{beamer}

     9 % \documentclass[handout]{beamer}

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    12 \usepackage{tikz}

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    13 \newcommand{\hyperlinkmovie}{}

    13 

    14 %\usepackage{movie15}

    14 % Modified from: generic-ornate-15min-45min.de.tex

    15 

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    17 % Note that in presentation mode 

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    21 

    22 

    38 \usepackage{times}

    24 %\usepackage{times}

    58 % My Macros

    43 % Macros

    59 \setbeamercolor{postit}{bg=yellow,fg=black}

    80 \newcommand{\inctime}[1]{\addtocounter{time}{#1}{\vspace*{0.1in}\tiny \thetime\ m}}

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

    81 

    53 

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

    85       \vfill \hfill

    57 

    86  \hfill \vfill

    58 %%% This is from Fernando's setup.

    87 }}}

    59 % \usepackage{color}

    88 

    60 % \definecolor{orange}{cmyk}{0,0.4,0.8,0.2}

    89 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    61 % % Use and configure listings package for nicely formatted code

    90 % Configuring the theme

    62 % \usepackage{listings}

    91 %\setbeamercolor{normal text}{fg=white}

    63 % \lstset{

    92 %\setbeamercolor{background canvas}{bg=black}

    64 %    language=Python,

    93 

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    68 %    showstringspaces=false,

    69 %    breaklines=true,

    70 %    postbreak = \space\dots

    71 % }

    98 \title[3D Plotting]{3D data Visualization}

    76 \title[Basic Python]{Python language: Data structures and functions}

    99 

    77 

   100 \author[FOSSEE] {FOSSEE}

    78 \author[FOSSEE Team] {The FOSSEE Group}

   103 \date[] {1 November, 2009\\Day 2, Session 5}

    81 \date[] {8 November, 2009\\Day 2, Session 3}

   104 

   107 %\pgfdeclareimage[height=0.75cm]{iitblogo}{iitblogo}

    84 %\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}

   108 %\logo{\pgfuseimage{iitblogo}}

    85 %\logo{\pgfuseimage{iitmlogo}}

   109 

    86 

   110 \AtBeginSection[]

   111 {

   112   \begin{frame}<beamer>

   113     \frametitle{Outline}      

   114     \tableofcontents[currentsection,currentsubsection]

   115   \end{frame}

   116 }

   140   \maketitle

   117   \titlepage

   149 \section{3D Data Visualization}

   126 \section{Functions}

   150 

   127 \subsection{Default arguments}

   128 \begin{frame}[fragile]

   129   \frametitle{Functions: default arguments}

   130   \begin{lstlisting}

   131 In []: greet = 'hello world'

   132 

   133 In []: greet.split()

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

   135 

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

   137 

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

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

   140                         ' 46', ' 55']

   141   \end{lstlisting}

   142 \end{frame}

   143 

   144 \begin{frame}[fragile]

   145   \frametitle{Functions: default arguments \ldots}

   146   \small

   147   \begin{lstlisting}

   148 def ask_ok(prompt, complaint='Yes or no!'):

   149     while True:

   150         ok = raw_input(prompt)

   151         if ok in ('y', 'ye', 'yes'):

   152             return True

   153         if ok in ('n', 'no', 'nop',

   154                             'nope'):

   155             return False

   156         print complaint

   157 

   158 ask_ok('?')

   159 ask_ok('?', '[Y/N]')

   160   \end{lstlisting}

   161 \end{frame} 

   162 

   163 \subsection{Keyword arguments}

   164 \begin{frame}[fragile]

   165   \frametitle{Functions: Keyword arguments}

   166 We have seen the following

   167   \begin{lstlisting}

   168 In []: legend(['sin(2y)'],

   169               loc='center')

   170 In []: plot(y, sin(y), 'g',

   171                  linewidth=2)

   172 In []: annotate('local max',

   173                  xy=(1.5, 1))

   174 In []: pie(science.values(),

   175             labels=science.keys())

   176   \end{lstlisting}

   177 \end{frame}

   178 

   179 \begin{frame}[fragile]

   180   \frametitle{Functions: keyword arguments \ldots}

   181   \small

   182   \begin{lstlisting}

   183 def ask_ok(prompt, complaint='Yes or no!'):

   184     while True:

   185         ok = raw_input(prompt)

   186         if ok in ('y', 'ye', 'yes'):

   187             return True

   188         if ok in ('n', 'no', 'nop',

   189                             'nope'):

   190             return False

   191         print complaint

   192 

   193 ask_ok(prompt='?')

   194 ask_ok(prompt='?', complaint='[y/n]')

   195 ask_ok(complaint='[y/n]', prompt='?')

   196 \end{lstlisting}

   197 \end{frame}

   198 

   199 \subsection{Built-in functions}

   152     \frametitle{What is visualization?}

   201   {Before writing a function}

   153     \Large

   202   \begin{itemize}

   154     \begin{center}

   203       \item Variety of builtin functions are available

   155     Visual representation of data

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

   156     \end{center}

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

   157 \end{frame}

   206       \item Refer here:

   158 

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

   159 

   208   \end{itemize}

   160 %% \begin{frame}

   209   \inctime{10} 

   161 %%     \frametitle{Is this new?}    

   210 \end{frame}

   162 %%     \begin{center}

   211 

   163 %%     We have moved from:

   212 \subsection{Exercises}

   164 %%     \end{center}

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

   165 %%     \begin{columns}

   214   Write a function to return the gcd of two numbers.

   166 %%     \column{}

   215 \end{frame}

   167 %%     \hspace*{-1in}    

   216 

   168 %%     \includegraphics[width=1.75in,height=1.75in, interpolate=true]{data/3832}      

   217 \begin{frame}{Problem 3.2}

   169 %%     \column{}\hspace*{-0.25in}

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

   170 %%     To

   219 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.

   171 %%     \column{}

   220 \end{frame}

   172 %%     \hspace*{-1in}

   221 

   173 %%     \includegraphics[width=1.75in, height=1.75in, interpolate=true]{data/torus}  

   222 \begin{frame}{Problem 3.3}

   174 %%     \end{columns}

   223   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).}

   175 %% \end{frame}

   224 \inctime{15}

   225 \end{frame}

   226 

   227 \section{Modules}

   228 \begin{frame}[fragile]

   229   \frametitle{\typ{from} \ldots \typ{import} magic}

   230   \begin{lstlisting}

   231 from scipy.interpolate import splrep

   232 from scipy.interpolate import splev

   233 

   234 from scipy.integrate import quad

   235 from scipy.integrate import odeint

   236 

   237 from scipy.optimize import fsolve

   238   \end{lstlisting}

   239 \emphbar{All the above statements import one function into your namespace}

   240 \end{frame}

   241 

   242 \begin{frame}[fragile]

   243   \frametitle{Running scripts from command line}

   244   \small

   245   \begin{itemize}

   246     \item Start cmd

   247     \item cd to Desktop

   248     \item python sine\_plot.py

   249   \end{itemize}

   250   \pause

   251   \begin{lstlisting}

   252 Traceback (most recent call last):

   253   File "sine_plot.py", line 1, in <module>

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

   255 NameError: name 'linspace' is not defined

   256   \end{lstlisting}

   257 \end{frame}

   258 

   259 \begin{frame}[fragile]

   260   \frametitle{Remedy}

   261   \emphbar{Adding what lines to sine\_plot.py makes this program work?}

   262   \begin{lstlisting}

   263 from scipy import *

   264   \end{lstlisting}

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

   266   \pause

   267   \begin{lstlisting}

   268 Traceback (most recent call last):

   269   File "sine_plot.py", line 4, in <module>

   270     plot(x, x, 'b')

   271 NameError: name 'plot' is not defined

   272   \end{lstlisting}

   273 \end{frame}

   274 

   275 \begin{frame}[fragile]

   276   \frametitle{Remedy \ldots}

   277   \emphbar{What should we add now?}

   278   \begin{lstlisting}

   279 from pylab import *

   280   \end{lstlisting}

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

   282 \end{frame}

   283 

   284 \begin{frame}[fragile]

   285   \frametitle{Modules}

   286   \begin{itemize}

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

   288     \item One can also use:

   289       \begin{lstlisting}

   290 In []: from scipy import *

   291 In []: from scipy import linspace

   292       \end{lstlisting}    

   293     \item What is the difference?

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

   295     \end{itemize}

   296 \end{frame}

   297 

   298 \begin{frame}[fragile]

   299   \frametitle{Package hierarchies}

   300   \begin{lstlisting}

   301 from scipy.interpolate import splev

   302 

   303 from scipy.integrate import quad

   304 

   305 from scipy.optimize import fsolve

   306   \end{lstlisting}

   307 \end{frame}

   308 

   309 \begin{frame}[fragile]

   310   \frametitle{from \ldots import in a conventional way!}

   311   \small

   312   \begin{lstlisting}

   313 from scipy import linspace, pi, sin

   314 from pylab import plot, legend, annotate

   315 from pylab import xlim, ylim

   316 

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

   318 plot(x, x, 'b')

   319 plot(x, -x, 'b')

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

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

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

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

   324 xlim(-5*pi, 5*pi)

   325 ylim(-5*pi, 5*pi)

   326   \end{lstlisting}

   327 \end{frame}

   328 

   329 \begin{frame}[fragile]

   330   \frametitle{from \ldots import in a conventional way!}

   331   \small

   332   \begin{lstlisting}

   333 import scipy

   334 import pylab

   335 

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

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

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

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

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

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

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

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

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

   345   \end{lstlisting}

   346 \end{frame}

   178     \frametitle{3D visualization}

   349   \frametitle{Modules: Standard library}

   179     \Large

   350   \begin{itemize}

   180     \begin{center}

   351   \item Very powerful, ``Batteries included''

   181         Harder but important

   352   \item Some standard modules:

   182     \end{center}

   353     \begin{itemize}

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

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

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

   357     \item Operating system interface: \typ{os}

   358     \item Regular expressions: \typ{re}

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

   360     \item And a whole lot more!

   361     \end{itemize}

   362   \item Check out the Python Library reference:

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

   364   \end{itemize}

   365 \inctime{5}

   366 \end{frame}

   367 

   368 \begin{frame}[fragile]

   369   \frametitle{Modules of special interest}

   370   \begin{description}[matplotlibfor2d]

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

   372 

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

   374             algebra, Fourier transforms, signal and image processing,

   375             genetic algorithms, ODE solvers, special functions, and more

   376 

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

   378   \end{description}

   379 \end{frame}

   380 

   381 \section{Objects}

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

   383   \begin{itemize}

   384     \item \typ{int}

   385     \item \typ{float}

   386     \item \typ{str}

   387     \item \typ{list}

   388     \item \typ{tuple}

   389     \item \typ{string}

   390     \item \typ{dictionary}

   391     \item \typ{function}

   392     \item User defined class is also an object!

   393   \end{itemize}

   394 \end {frame}

   395 

   396 \begin{frame}[fragile]

   397 \frametitle{Using Objects}

   398   \begin{itemize}

   399     \item Creating Objects

   400     \begin{itemize}

   401       \item Initialization

   402     \end{itemize}

   403     \begin{lstlisting}

   404 In []: a = str()

   405 

   406 In []: b = "Hello World"

   407     \end{lstlisting}

   408     \item Object Manipulation

   409     \begin{itemize}

   410       \item Object methods

   411       \item ``.'' operator

   412     \end{itemize}

   413   \begin{lstlisting}

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

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

   416     \end{lstlisting}

   417   \end{itemize}

   418 \end{frame}

   419 

   420 \begin{frame}[fragile]

   421   \frametitle{Objects provide consistency}

   422   \small

   423   \begin{lstlisting}

   424 for element in (1, 2, 3):

   425     print element

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

   427     print key

   428 for char in "123":

   429     print char

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

   431     print line

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

   433     print line

   434   \end{lstlisting}

   435   \inctime{10}

   186     \frametitle{Is this Graphics?}

   439   \frametitle{What did we learn?}

   187     \Large

   440   \begin{itemize}

   188     \begin{center}

   441     \item Functions: Default and Keyword arguments

   189         Visualization is about data!

   442     \item Modules

   190     \end{center}

   443     \item Objects

   191 \end{frame}

   192 

   193 \begin{frame}

   194     \frametitle{Examples: trajectory in space}

   195     \Large

   196     \begin{center}

   197         \pgfimage[width=2.5in]{MEDIA/m2/mlab/plot3d_ex}

   198     \end{center}

   199 \end{frame}

   200 

   201 \begin{frame}

   202     \frametitle{Examples: Fire in a room}

   203     \Large

   204     \begin{center}

   205         Demo of data

   206     \end{center}

   207 \inctime{10}

   208 \end{frame}

   209 

   210 \section{Tools available}

   211 

   212 \subsection{mlab}

   213 

   214 \begin{frame}

   215     {Overview}

   216     \Large

   217     \begin{itemize}

   218         \item Simple

   219         \item Convenient

   220         \item Full-featured

   221     \end{itemize}

   222 \end{frame}

   223 

   224 \begin{frame}[fragile]

   225 

   226     \frametitle{Getting started}

   227     \myemph{\Large Vanilla:}

   228     \begin{lstlisting}[language=bash]

   229         $ ipython -wthread

   230     \end{lstlisting}

   231     \myemph{\Large with Pylab:}

   232     \begin{lstlisting}[language=bash]

   233         $ ipython -pylab -wthread

   234     \end{lstlisting}

   235 \end{frame}

   236 

   237 \begin{frame}[fragile]

   238     \frametitle{Using mlab}

   239 

   240     \begin{lstlisting}

   241 In []:from enthought.mayavi import mlab

   242     \end{lstlisting}

   243 

   244     \vspace*{0.5in}

   245 

   246     \myemph{\Large Try these}

   247 

   248     \vspace*{0.25in}

   249 

   250     \begin{lstlisting}

   251 In []: mlab.test_<TAB>

   252 In []: mlab.test_contour3d()

   253 In []: mlab.test_contour3d??

   254     \end{lstlisting}

   255 \end{frame}

   256 

   257 \begin{frame}

   258     {Exploring the view}

   259     \begin{columns}

   260         \column{0.6\textwidth}

   261     \pgfimage[width=3in]{MEDIA/m2/contour3d}

   262         \column{0.4\textwidth}

   263         \begin{itemize}

   264             \item Mouse

   265             \item Keyboard

   266             \item Toolbar

   267             \item Mayavi icon\pgfimage[width=0.2in]{MEDIA/m2/m2_icon}

   268         \end{itemize}

   269     \end{columns}

   270 \end{frame}

   271 

   272 \begin{frame}[fragile]

   273     \frametitle{\mlab\ plotting functions}

   274     \begin{columns}

   275         \column{0.25\textwidth}

   276         \myemph{\Large 0D data}

   277         \column{0.5\textwidth}

   278     \pgfimage[width=2in]{MEDIA/m2/mlab/points3d_ex}

   279     \end{columns}

   280 

   281     \begin{lstlisting}

   282 In []: t = linspace(0, 2*pi, 50)

   283 In []: u = cos(t) * pi

   284 In []: x, y, z = sin(u), cos(u), sin(t)

   285     \end{lstlisting}

   286     \emphbar{\PythonCode{In []: mlab.points3d(x, y, z)}}

   287 \end{frame}

   288 

   289 \begin{frame}

   290   \begin{columns}

   291         \column{0.25\textwidth}

   292         \myemph{\Large 1D data}

   293         \column{0.5\textwidth}

   294         \pgfimage[width=2.5in]{MEDIA/m2/mlab/plot3d_ex}

   295   \end{columns}

   296   \emphbar{\PythonCode{In []: mlab.plot3d(x, y, z, t)}}

   297 

   298     Plots lines between the points

   299     

   300 \end{frame}

   301 

   302 \begin{frame}[fragile]

   303     \begin{columns}

   304         \column{0.25\textwidth}

   305         \myemph{\Large 2D data}

   306         \column{0.5\textwidth}

   307         \pgfimage[width=2in]{MEDIA/m2/mlab/surf_ex}

   308     \end{columns}            

   309     \begin{lstlisting}

   310 In []: x, y = mgrid[-3:3:100j,-3:3:100j]

   311 In []: z = sin(x*x + y*y)

   312     \end{lstlisting}

   313 

   314     \emphbar{\PythonCode{In []: mlab.surf(x, y, z)}}

   315 

   316     \alert{Assumes the points are rectilinear}

   317 

   318 \end{frame}

   319 

   320 \begin{frame}[fragile]

   321   \frametitle{mgrid}

   322   \begin{lstlisting}

   323 In []: mgrid[0:3,0:3]

   324 Out[]: 

   325 array([[[0, 0, 0],

   326         [1, 1, 1],

   327         [2, 2, 2]],

   328 

   329        [[0, 1, 2],

   330         [0, 1, 2],

   331         [0, 1, 2]]])

   332 

   333 In []: mgrid[-1:1:5j]

   334 Out[]: array([-1., -0.5,  0.,  0.5,  1.])

   335 \end{lstlisting}

   336 \end{frame}

   337 

   338 \begin{frame}[fragile]

   339   \frametitle{Example}

   340   \begin{lstlisting}

   341 In []: x, y = mgrid[-1:1:5j, -1:1:5j]

   342 In []: z = x*x + y*y

   343 

   344 In []: z

   345 Out[]: 

   346 array([[ 2.  , 1.25, 1.  , 1.25, 2.  ],

   347        [ 1.25, 0.5 , 0.25, 0.5 , 1.25],

   348        [ 1.  , 0.25, 0.  , 0.25, 1.  ],

   349        [ 1.25, 0.5 , 0.25, 0.5 , 1.25],

   350        [ 2.  , 1.25, 1.  , 1.25, 2.  ]])

   351 \end{lstlisting}

   352 \end{frame}

   353 

   354 \begin{frame}[fragile]

   355     \myemph{\Large 2D data: \texttt{mlab.mesh}}

   356     \vspace*{0.25in}

   357 

   358     \emphbar{\PythonCode{In []: mlab.mesh(x, y, z)}}

   359 

   360     \alert{Points needn't be regular}

   361 

   362     \vspace*{0.25in}

   363 \begin{lstlisting}

   364 In []: phi, theta = mgrid[0:pi:20j, 

   365 ...                         0:2*pi:20j]

   366 In []: x = sin(phi)*cos(theta)

   367 In []: y = sin(phi)*sin(theta)

   368 In []: z = cos(phi)

   369 In []: mlab.mesh(x, y, z, 

   370 ...           representation=

   371 ...           'wireframe')

   372 \end{lstlisting}

   373 

   374 \end{frame}

   375 

   376 \begin{frame}[fragile]

   377 

   378   \begin{columns}

   379         \column{0.25\textwidth}

   380         \myemph{\Large 3D data}

   381         \column{0.5\textwidth}

   382         \pgfimage[width=1.5in]{MEDIA/m2/mlab/contour3d}\\        

   383     \end{columns}

   384 \begin{lstlisting}

   385 In []: x, y, z = mgrid[-5:5:64j, 

   386 ...                -5:5:64j, 

   387 ...                -5:5:64j]

   388 In []: mlab.contour3d(x*x*0.5 + y*y + 

   389                    z*z*2)

   390 \end{lstlisting}

   391 \end{frame}

   392 

   393 \begin{frame}[fragile]

   394 

   395     \myemph{\Large 3D vector data: \PythonCode{mlab.quiver3d}}

   396     \vspace*{0.25in}

   397 

   398     \pgfimage[width=2in]{MEDIA/m2/mlab/quiver3d_ex}\\

   399     

   400 \begin{lstlisting}

   401 In []: mlab.test_quiver3d()

   402 \end{lstlisting}

   403 

   404 \emphbar{\PythonCode{obj = mlab.quiver3d(x, y, z, u, v, w)}}

   405 \inctime{20}

   406 \end{frame}

   407 

   408 

   409 \subsection{Mayavi2}

   410 

   411 \begin{frame}

   412   \frametitle{Introduction to Mayavi}

   413   \begin{itemize}

   414   \item Most scientists not interested in details of visualization

   415   \item Visualization of data files with a nice UI

   416   \item Interactive visualization of data (think Matlab)

   417   \item Embedding visualizations in applications

   418   \item Customization

   419   \end{itemize}

   420   \pause

   421   \begin{block}{The Goal}

   422       Provide a \alert{flexible} library/app for all of these needs!

   423   \end{block}

   424 \end{frame}

   425 

   426 \begin{frame}

   427     {Overview of features}

   428       \vspace*{-0.3in}

   429   \begin{center}    

   430     \hspace*{-0.2in}\pgfimage[width=5in]{MEDIA/m2/m2_app3_3}

   431   \end{center}    

   432 \end{frame}

   433 

   434 

   435 \begin{frame}

   436     \frametitle{Mayavi in applications}

   437       \vspace*{-0.3in}

   438   \begin{center}    

   439     \hspace*{-0.2in}\pgfimage[width=4.5in]{MEDIA/m2/m2_envisage}

   440   \end{center}

   441 \end{frame}

   442 

   443 \begin{frame}

   444     \frametitle{Live in your dialogs}

   445       \vspace*{0.1in}

   446   \begin{center}    

   447     \hspace*{-0.2in}\pgfimage[width=2.5in]{MEDIA/m2/mlab_tui}

   448   \end{center}

   449 \end{frame}

   450 

   451 \begin{frame}

   452     {Exploring the documentation}

   453     \begin{center}

   454     \pgfimage[width=4in]{MEDIA/m2/m2_ug_doc}

   455     \end{center}

   456 \end{frame}

   457 

   458 

   459 \begin{frame}

   460   \frametitle{Summary}

   461       \begin{itemize}

   462           \item \url{http://code.enthought.com/projects/mayavi}

   463           \item Uses VTK (\url{www.vtk.org})

   464           \item BSD license

   465           \item Linux, win32 and Mac OS X

   466           \item Highly scriptable

   467           \item Embed in Traits UIs (wxPython and PyQt4)

   468           \item Envisage Plugins

   469           \item Debian/Ubuntu/Fedora

   470           \item \alert{Pythonic}

   471       \end{itemize}

   472     

   473       \inctime{10}

   474 

   475 \end{frame}

   476 

   477 \begin{frame}

   478     {Getting hands dirty!}

   479 

   480         \begin{block}{Motivational problem}

   481         Atmospheric data of temperature over the surface of the earth.

   482         Let temperature ($T$) vary linearly with height ($z$):

   483         \begin{center}            

   484         $T = 288.15 - 6.5z$

   485         \end{center}

   486         \end{block}

   487 \end{frame}

   488 

   489 \begin{frame}[fragile]

   490     \frametitle{Simple solution}

   491 

   492     \begin{lstlisting}

   493 lat = linspace(-89, 89, 37)

   494 lon = linspace(0, 360, 37)

   495 z = linspace(0, 100, 11)

   496     \end{lstlisting}

   497 \pause

   498     \begin{lstlisting}

   499 x, y, z = mgrid[0:360:37j,-89:89:37j,

   500                 0:100:11j]

   501 t = 288.15 - 6.5*z

   502 mlab.contour3d(x, y, z, t)

   503 mlab.outline()

   504 mlab.colorbar()

   505     \end{lstlisting}

   506 \end{frame}

   507 

   508 \begin{frame}[fragile]

   509     \frametitle{Exercise: Lorenz equation}

   510     \begin{columns}

   511         \column{0.25\textwidth}

   512         \begin{eqnarray*}

   513         \frac{d x}{dt} &=& s (y-x)\\

   514         \frac{d y}{d t} &=& rx -y -xz\\

   515         \frac{d z}{d t} &=& xy - bz\\

   516         \end{eqnarray*}

   517         \column{0.25\textwidth}

   518         Let $s=10,$

   519         $r=28,$ 

   520         $b=8./3.$

   521     \end{columns}

   522     \structure{\Large Region of interest}

   523   \begin{lstlisting}

   524 x, y, z = mgrid[-50:50:20j,-50:50:20j,

   525                 -10:60:20j]

   526   \end{lstlisting}

   527 \inctime{20}

   528 

   529 \end{frame}

   530 \begin{frame}[fragile]

   531     \frametitle{Solution}

   532   \begin{lstlisting}

   533 def lorenz(x,y,z,s=10.,r=28.,b=8./3.):

   534     u = s*(y-x)

   535     v = r*x-y-x*z

   536     w = x*y-b*z

   537     return u,v,w

   538 x,y,z = mgrid [-50:50:20j,-50:50:20j,

   539                     -10:60:20j ]

   540 u,v,w = lorenz( x , y , z )

   541 # Your plot here

   542 #

   543 mlab.show()

   544 

   545   \end{lstlisting}

   546 \end{frame}

   547 

   548 \begin{frame}

   549   \frametitle{We have covered:}

   550   \begin{itemize}

   551   \item Need of visualization.

   552   \item Using mlab to create 3 D plots.

   553   \item Mayavi Toolkit.