1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     2 %Tutorial slides on Python.

     3 %

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

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

     6 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     7 

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

     9 %\documentclass[draft]{beamer}

    10 %\documentclass[compress,handout]{beamer}

    11 %\usepackage{pgfpages} 

    12 %\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]

    13 

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

    15 \mode<presentation>

    16 {

    17   \usetheme{Warsaw}

    18   \useoutertheme{split}

    19   \setbeamercovered{transparent}

    20 }

    21 

    22 \usepackage[english]{babel}

    23 \usepackage[latin1]{inputenc}

    24 %\usepackage{times}

    25 \usepackage[T1]{fontenc}

    26 

    27 % Taken from Fernando's slides.

    28 \usepackage{ae,aecompl}

    29 \usepackage{mathpazo,courier,euler}

    30 \usepackage[scaled=.95]{helvet}

    31 

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

    33 

    34 \usepackage{listings}

    35 \lstset{language=Python,

    36     basicstyle=\ttfamily\bfseries,

    37     commentstyle=\color{red}\itshape,

    38   stringstyle=\color{darkgreen},

    39   showstringspaces=false,

    40   keywordstyle=\color{blue}\bfseries}

    41 

    42 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    43 % Macros

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

    45 \newcommand{\emphbar}[1]

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

    47       {#1}

    48  \end{beamercolorbox}

    49 }

    50 \newcounter{time}

    51 \setcounter{time}{0}

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

    53 

    54 \newcommand{\typ}[1]{\texttt{#1}}

    55 

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

    57 

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

    59 % \usepackage{color}

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

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

    62 % \usepackage{listings}

    63 % \lstset{

    64 %    language=Python,

    65 %    basicstyle=\small\ttfamily,

    66 %    commentstyle=\ttfamily\color{blue},

    67 %    stringstyle=\ttfamily\color{orange},

    68 %    showstringspaces=false,

    69 %    breaklines=true,

    70 %    postbreak = \space\dots

    71 % }

    72 

    73 

    74 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    75 % Title page

    76 \title[Basic Python]{Python:\\A formal approach}

    77 

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

    79 

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

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

    82 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    83 

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

    85 %\logo{\pgfuseimage{iitmlogo}}

    86 

    87 

    88 %% Delete this, if you do not want the table of contents to pop up at

    89 %% the beginning of each subsection:

    90 \AtBeginSubsection[]

    91 {

    92   \begin{frame}<beamer>

    93     \frametitle{Outline}

    94     \tableofcontents[currentsection,currentsubsection]

    95   \end{frame}

    96 }

    97 

    98 \AtBeginSection[]

    99 {

   100   \begin{frame}<beamer>

   101     \frametitle{Outline}

   102     \tableofcontents[currentsection,currentsubsection]

   103   \end{frame}

   104 }

   105 

   106 % If you wish to uncover everything in a step-wise fashion, uncomment

   107 % the following command: 

   108 %\beamerdefaultoverlayspecification{<+->}

   109 

   110 %\includeonlyframes{current,current1,current2,current3,current4,current5,current6}

   111 

   112 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   113 % DOCUMENT STARTS

   114 \begin{document}

   115 

   116 \begin{frame}

   117   \titlepage

   118 \end{frame}

   119 

   120 \begin{frame}

   121   \frametitle{Outline}

   122   \tableofcontents

   123   % You might wish to add the option [pausesections]

   124 \end{frame}

   125 

   126 \section{Data structures}

   127 \subsection{Lists}

   128 \begin{frame}[fragile]

   129   \frametitle{Lists}

   130 \begin{block}{We already know that}

   131   \begin{lstlisting}

   132 num = [1, 2, 3, 4, 5, 6, 7, 8]

   133   \end{lstlisting}

   134 \centerline{is a list}

   135 \end{block}

   136 \end{frame}

   137 

   138 \begin{frame}[fragile]

   139   \frametitle{Lists: methods}

   140   \begin{lstlisting}

   141 In []: num.reverse()

   142 In []: num

   143 Out[]: [8, 7, 6, 5, 4, 3, 2, 1]

   144 

   145 In []: num.extend([0, -1, -2])

   146 In []: num

   147 Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1]

   148 

   149 In []: num.remove(0)

   150 In []: num

   151 Out[]: [8, 7, 6, 5, 4, 3, 2, 1, -1]

   152   \end{lstlisting}

   153 \end{frame}

   154 

   155 \begin{frame}[fragile]

   156 \frametitle{List containership}

   157 \begin{lstlisting}

   158 In []: a = 8

   159 

   160 In []: a in num

   161 Out[]: True

   162 

   163 In []: b = 10

   164 In []: b in num

   165 Out[]: False

   166 

   167 In []: b not in num

   168 Out[]: True

   169 \end{lstlisting}

   170 \end{frame}

   171 

   172 \subsection{Tuples}

   173 \begin{frame}[fragile]

   174 \frametitle{Tuples: Immutable lists}

   175 \begin{lstlisting}

   176 In []: t = (1, 2, 3, 4, 5, 6, 7, 8)

   177 In []: t[0] + t[3] + t[-1]

   178 Out[]: 13

   179 \end{lstlisting}

   180 \begin{block}{Note:}

   181 \begin{itemize}

   182   \item Tuples are immutable - cannot be changed

   183 \end{itemize}

   184 \end{block}

   185   \inctime{10}

   186 \end{frame}

   187 

   188 \begin{frame}

   189   {A classic problem}

   190   \begin{block}

   191     {Interchange values}

   192     How to interchange values of two variables? 

   193   \end{block}

   194   \pause

   195   \begin{block}{Note:}

   196     This Python idiom works for all types of variables.\\

   197 They need not be of the same type!

   198   \end{block}

   199 \end{frame}

   200 

   201 \subsection{Dictionaries}

   202 \begin{frame}[fragile]

   203   \frametitle{Dictionaries: Recall}

   204   \begin{lstlisting}

   205 In []: player = {'Mat': 134,'Inn': 233,

   206           'Runs': 10823, 'Avg': 52.53}

   207 

   208 In []: player['Avg']

   209 Out[]: 52.530000000000001

   210   \end{lstlisting}

   211   \begin{block}{Note!}

   212     Duplicate keys are not allowed!\\

   213     Dictionaries are iterable through keys.

   214   \end{block}

   215 \end{frame}

   216 

   217 \begin{frame} {Problem Set 2.1: Problem 2.1.1}

   218 You are given date strings of the form ``29, Jul 2009'', or ``4 January 2008''. In other words a number a string and another number, with a comma sometimes separating the items.Write a function that takes such a string and returns a tuple (yyyy, mm, dd) where all three elements are ints.

   219 \end{frame}

   220 

   221 \subsection{Set}

   222 \begin{frame}[fragile]

   223   \frametitle{Set}

   224     \begin{itemize}

   225       \item Simplest container, mutable

   226       \item No ordering, no duplicates

   227       \item usual suspects: union, intersection, subset \ldots

   228       \item >, >=, <, <=, in, \ldots

   229     \end{itemize}

   230     \begin{lstlisting}

   231 >>> f10 = set([1,2,3,5,8])

   232 >>> p10 = set([2,3,5,7])

   233 >>> f10|p10

   234 set([1, 2, 3, 5, 7, 8])

   235 >>> f10&p10

   236 set([2, 3, 5])

   237 >>> f10-p10

   238 set([8, 1])

   239 \end{lstlisting}

   240 \end{frame}

   241 

   242 \begin{frame}[fragile]

   243   \frametitle{Set}

   244     \begin{lstlisting}

   245 >>> p10-f10, f10^p10

   246 set([7]), set([1, 7, 8])

   247 >>> set([2,3]) < p10

   248 True

   249 >>> set([2,3]) <= p10

   250 True

   251 >>> 2 in p10

   252 True

   253 >>> 4 in p10

   254 False

   255 >>> len(f10)

   256 5

   257 \end{lstlisting}

   258 \end{frame}

   259 

   260 \begin{frame}

   261   \frametitle{Problem set 2.2}

   262   \begin{description}

   263     \item[2.2.1] Given a dictionary of the names of students and their marks, identify how many duplicate marks are there? and what are these?

   264     \item[2.2.2] Given a string of the form ``4-7, 9, 12, 15'' find the numbers missing in this list for a given range.

   265 \end{description}

   266 \inctime{15}

   267 \end{frame}

   268 

   269 \section{Functions}

   270 \begin{frame}[fragile]

   271   \frametitle{Functions}

   272   \begin{itemize}

   273     \item \kwrd{def} - keyword to define a function

   274     \item Arguments are local to a function

   275     \item Docstrings are important!

   276     \item Functions can return multiple values

   277   \end{itemize}

   278 \end{frame}

   279 

   280 \begin{frame}[fragile]

   281   \frametitle{Functions: example}

   282   \begin{lstlisting}

   283 def signum( r ):

   284     """returns 0 if r is zero

   285     -1 if r is negative

   286     +1 if r is positive"""

   287     if r < 0:

   288         return -1

   289     elif r > 0:

   290         return 1

   291     else:

   292         return 0

   293   \end{lstlisting}

   294 \end{frame}

   295 

   296 \begin{frame}[fragile]

   297   {What does this function do?}

   298 \begin{lstlisting}

   299 def what( n ):

   300     i = 1

   301     while i * i < n:

   302         i += 1

   303     return i * i == n, i

   304   \end{lstlisting}

   305 \end{frame}

   306 

   307 \subsection{Default arguments}

   308 \begin{frame}[fragile]

   309   \frametitle{Functions: default arguments}

   310   \small

   311   \begin{lstlisting}

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

   313     while True:

   314         ok = raw_input(prompt)

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

   316             return True

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

   318                   'nope'): 

   319             return False

   320         print complaint

   321 

   322 ask_ok('?')

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

   324   \end{lstlisting}

   325 \end{frame}

   326 

   327 \subsection{Built-in functions}

   328 \begin{frame}

   329   {Before writing a function}

   330   \begin{itemize}

   331       \item Variety of builtin functions are available

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

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

   334       \item Refer here:

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

   336   \end{itemize}

   337   \inctime{10} 

   338 \end{frame}

   339 

   340 \subsection{Exercises}

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

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

   343 \end{frame}

   344 

   345 \begin{frame}{Problem 3.2}

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

   347 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.

   348 \end{frame}

   349 

   350 \begin{frame}{Problem 3.3}

   351   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).}

   352 \inctime{15}

   353 \end{frame}

   354 

   355 \section{Modules}

   356 \begin{frame}[fragile]

   357     {Modules}

   358 \begin{lstlisting}

   359 >>> sqrt(2)

   360 Traceback (most recent call last):

   361   File "<stdin>", line 1, in <module>

   362 NameError: name 'sqrt' is not defined

   363 >>> import math        

   364 >>> math.sqrt(2)

   365 1.4142135623730951

   366 \end{lstlisting}

   367 \end{frame}

   368 

   369 \begin{frame}[fragile]

   370     {Modules}

   371   \begin{itemize}

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

   373     \item One can also use:

   374       \begin{lstlisting}

   375 >>> from math import sqrt

   376 >>> from math import *

   377       \end{lstlisting}    

   378     \item What is the difference?

   379     \item \alert{Use the latter only in interactive mode}

   380     \end{itemize}

   381   \emphbar{Package hierarchies}

   382       \begin{lstlisting}

   383 >>> from os.path import exists

   384       \end{lstlisting}

   385 \end{frame}

   386 

   387 \begin{frame}

   388   \frametitle{Modules: Standard library}

   389   \begin{itemize}

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

   391   \item Some standard modules:

   392     \begin{itemize}

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

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

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

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

   397     \item Regular expressions: \typ{re}

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

   399     \item And a whole lot more!

   400     \end{itemize}

   401   \item Check out the Python Library reference:

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

   403   \end{itemize}

   404 \inctime{5}

   405 \end{frame}

   406 

   407 \section{Coding Style}

   408 \begin{frame}{Readability and Consistency}

   409     \begin{itemize}

   410         \item Readability Counts!\\Code is read more often than its written.

   411         \item Consistency!

   412         \item Know when to be inconsistent.

   413       \end{itemize}

   414 \end{frame}

   415 

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

   417   \begin{lstlisting}

   418     amount = 12.68

   419     denom = 0.05

   420     nCoins = round(amount/denom)

   421     rAmount = nCoins * denom

   422   \end{lstlisting}

   423   \pause

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

   425     Naming is 80\% of programming

   426   \end{block}

   427 \end{frame}

   428 

   429 \begin{frame}[fragile]

   430   \frametitle{Code Layout}

   431   \begin{itemize}

   432         \item Indentation

   433         \item Tabs or Spaces??

   434         \item Maximum Line Length

   435         \item Blank Lines

   436         \item Encodings

   437    \end{itemize}

   438 \end{frame}

   439 

   440 \begin{frame}{Whitespaces in Expressions}

   441   \begin{itemize}

   442         \item When to use extraneous whitespaces??

   443         \item When to avoid extra whitespaces??

   444         \item Use one statement per line

   445    \end{itemize}

   446 \end{frame}

   447 

   448 \begin{frame}{Comments}

   449   \begin{itemize}

   450         \item No comments better than contradicting comments

   451         \item Block comments

   452         \item Inline comments

   453    \end{itemize}

   454 \end{frame}

   455 

   456 \begin{frame}{Docstrings}

   457   \begin{itemize}

   458         \item When to write docstrings?

   459         \item Ending the docstrings

   460         \item One liner docstrings

   461    \end{itemize}

   462 More information at PEP8: http://www.python.org/dev/peps/pep-0008/

   463 \inctime{5}

   464 \end{frame}

   465 

   466 \section{Objects}

   467 \begin{frame}{Objects in general}

   468     \begin{itemize}

   469         \item What is an Object? (Types and classes)

   470         \item identity

   471         \item type

   472         \item method

   473       \end{itemize}

   474 \end{frame}

   475 

   476 \begin{frame}{Almost everything is an Object!}

   477   \begin{itemize}

   478     \item \typ{list}

   479     \item \typ{tuple}

   480     \item \typ{string}

   481     \item \typ{dictionary}

   482     \item \typ{function}

   483     \item Of course, user defined class objects!

   484   \end{itemize}

   485 \end {frame}

   486 

   487 \begin{frame}{Using Objects}

   488   \begin{itemize}

   489     \item Creating Objects: Initialization

   490     \item Object Manipulation: Object methods and ``.'' operator

   491   \end{itemize}

   492 \end{frame}

   493 

   494 \begin{frame}[fragile]

   495   \frametitle{Objects provide consistency}

   496   \small

   497   \begin{lstlisting}

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

   499     print element

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

   501     print key

   502 for char in "123":

   503     print char

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

   505     print line

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

   507     print line

   508   \end{lstlisting}

   509 \inctime{10}

   510 \end{frame}

   511 

   512 \begin{frame}

   513   \frametitle{What did we learn?}

   514   \begin{itemize}

   515     \item Lists, Tuples, Dictionaries, Sets: creation and manipulation

   516     \item More about functions

   517     \item Coding style

   518     \item Objects: creation and manipulation

   519   \end{itemize}

   520 \end{frame}

   521 

   522 \end{document}