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

     2 % Tutorial slides on Python.

     3 %

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

     5 % Copyright (c) 2005-2008, Prabhu Ramachandran

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

     7 

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

     9 %\documentclass[draft]{beamer}

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

    15 \mode<presentation>

    16 {

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    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

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    47       {#1}

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    49 }

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    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:\\Advanced Python data structures, Functions and Debugging}

    77 

    78 \author[FOSSEE Team] {Asokan Pichai\\Prabhu Ramachandran}

    79 

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

    81 \date[] {10, October 2009}

    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 

    99 % If you wish to uncover everything in a step-wise fashion, uncomment

   100 % the following command: 

   101 %\beamerdefaultoverlayspecification{<+->}

   102 

   103 %\includeonlyframes{current,current1,current2,current3,current4,current5,current6}

   104 

   105 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   106 % DOCUMENT STARTS

   107 \begin{document}

   108 

   109 \begin{frame}

   110   \titlepage

   111 \end{frame}

   112 

   113 \section{Python}

   114 

   115 \subsection{Dictionary}

   116 \begin{frame}{Dictionary}

   117   \begin{itemize}

   118     \item aka associative arrays, key-value pairs, hashmaps, hashtables \ldots    

   119     \item \typ{ d = \{ ``Hitchhiker's guide'' : 42, ``Terminator'' : ``I'll be back''\}}

   120     \item lists and tuples index: 0 \ldots n

   121     \item dictionaries index using strings

   122     \item aka key-value pairs

   123     \item what can be keys?

   124   \end{itemize}

   125 \end{frame}

   126 

   127 \begin{frame}{Dictionary \ldots }

   128   \begin{itemize}

   129     \item \alert{Unordered}

   130       \begin{block}{Standard usage}

   131         for key in dict:\\

   132             <use> dict[key] \# => value

   133       \end{block}

   134     \item \typ{d.keys()} returns a list

   135     \item can we have duplicate keys?

   136   \end{itemize}

   137   \inctime{5}

   138 \end{frame}

   139 

   140 \begin{frame} {Problem Set 2.1}

   141   \begin{description}

   142 \item[2.1.1] 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.

   143     \item[2.1.2] Count word frequencies in a file.

   144     \item[2.1.3] Find the most used Python keywords in your Python code (import keyword).

   145 \end{description}

   146 

   147 \inctime{10}

   148 \end{frame}

   149 

   150 \subsection{Set}

   151 \begin{frame}[fragile]

   152   \frametitle{Set}

   153     \begin{itemize}

   154       \item Simplest container, mutable

   155       \item No ordering, no duplicates

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

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

   158     \end{itemize}

   159     \begin{lstlisting}

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

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

   162 >>> f10|p10

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

   164 >>> f10&p10

   165 set([2, 3, 5])

   166 >>> f10-p10

   167 set([8, 1])

   168 \end{lstlisting}

   169 \end{frame}

   170 

   171 \begin{frame}[fragile]

   172   \frametitle{Set}

   173     \begin{lstlisting}

   174 >>> p10-f10, f10^p10

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

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

   177 True

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

   179 True

   180 >>> 2 in p10

   181 True

   182 >>> 4 in p10

   183 False

   184 >>> len(f10)

   185 5

   186 \end{lstlisting}

   187 \inctime{5}

   188 \end{frame}

   189 

   190 

   191 \begin{frame}

   192   \frametitle{Problem set 2.2}

   193   \begin{description}

   194     \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?

   195     \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.

   196 \end{description}

   197 \inctime{10}

   198 \end{frame}

   199 

   200 \subsection{Functions Reloaded!}

   201 \begin{frame}[fragile]

   202     \frametitle{Advanced functions}

   203     \begin{itemize}

   204         \item default args

   205         \item var args

   206         \item keyword args

   207         \item scope

   208         \item \typ{global}

   209       \end{itemize}

   210 \end{frame}

   211 

   212 \begin{frame}[fragile]

   213   \frametitle{Functions: default arguments}

   214   \small

   215   \begin{lstlisting}

   216 def ask_ok(prompt, retries=4,

   217            complaint='Yes or no!'):

   218     while True:

   219         ok = raw_input(prompt)

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

   221             return True

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

   223                   'nope'): 

   224             return False

   225         retries = retries - 1

   226         if retries < 0: 

   227             raise IOError, 'bad user'

   228         print complaint

   229   \end{lstlisting}

   230 \end{frame}

   231 

   232 \begin{frame}[fragile]

   233   \frametitle{Functions: keyword arguments}

   234   \small

   235   \begin{lstlisting}

   236 def parrot(voltage, state='a stiff', 

   237            action='voom', type='Royal Blue'):

   238     print "-- This parrot wouldn't", action,

   239     print "if you supply", voltage, "Volts."

   240     print "-- Lovely plumage, the", type

   241     print "-- It's", state, "!"

   242 

   243 parrot(1000)

   244 parrot(action = 'VOOOOOM', voltage = 1000000)

   245 parrot('a thousand',

   246        state = 'pushing up the daisies')

   247 parrot('a million', 'bereft of life', 'jump')

   248 \end{lstlisting}

   249 \end{frame}

   250 

   251 \begin{frame}[fragile]

   252   \frametitle{Functions: arbitrary argument lists}

   253   \begin{itemize}

   254   \item Arbitrary number of arguments using \verb+*args+ or

   255     \verb+*whatever+

   256   \item Keyword arguments using \verb+**kw+

   257   \item Given a tuple/dict how do you call a function?

   258     \begin{itemize}

   259     \item Using argument unpacking

   260     \item For positional arguments: \verb+foo(*[5, 10])+

   261     \item For keyword args: \verb+foo(**{'a':5, 'b':10})+

   262     \end{itemize}

   263   \end{itemize}

   264 \end{frame}

   265 

   266   \begin{frame}[fragile]

   267 \begin{lstlisting}

   268 def foo(a=10, b=100):

   269     print a, b

   270 def func(*args, **keyword):

   271     print args, keyword

   272 # Unpacking:

   273 args = [5, 10]

   274 foo(*args)

   275 kw = {'a':5, 'b':10}

   276 foo(**kw)

   277 \end{lstlisting}

   278     \inctime{15} 

   279 \end{frame}

   280 

   281 \subsection{Functional programming}

   282 \begin{frame}[fragile]

   283     \frametitle{Functional programming}

   284 What is the basic idea?\\

   285 Why is it interesting?\\

   286 \typ{map, reduce, filter}\\

   287 list comprehension\\

   288 generators

   289     \inctime{15} 

   290 \end{frame}

   291 

   292 \subsection{Debugging}

   293 \begin{frame}[fragile]

   294  \frametitle{Errors}

   295  \begin{lstlisting}

   296 >>> while True print 'Hello world'

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

   298     while True print 'Hello world'

   299                    ^

   300 SyntaxError: invalid syntax

   301 \end{lstlisting}

   302 \end{frame}

   303 

   304 \begin{frame}[fragile]

   305  \frametitle{Exceptions}

   306  \begin{lstlisting}

   307 >>> print spam

   308 Traceback (most recent call last):

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

   310 NameError: name 'spam' is not defined

   311 

   312 >>> 1 / 0

   313 Traceback (most recent call last):

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

   315 ZeroDivisionError: integer division 

   316 or modulo by zero

   317 \end{lstlisting}

   318 \end{frame}

   319 

   320 \begin{frame}[fragile]

   321     \frametitle{Debugging effectively}

   322 

   323     \begin{itemize}

   324         \item  \kwrd{print} based strategy

   325         \item Process: Hypothesis, test, refine, rinse-repeat

   326         \item Using \typ{\%debug} and \typ{\%pdb} in IPython

   327     \end{itemize}

   328     \inctime{15} 

   329 \end{frame}

   330 

   331 \begin{frame}[fragile]

   332 \frametitle{Debugging: example}

   333 \small

   334 \begin{lstlisting}

   335 >>> import pdb

   336 >>> import mymodule

   337 >>> pdb.run('mymodule.test()')

   338 > <string>(1)<module>()

   339 (Pdb) continue

   340 Traceback (most recent call last):

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

   342   File "/usr/lib/python2.6/pdb.py", line 1207, in run

   343     Pdb().run(statement, globals, locals)

   344   File "/usr/lib/python2.6/bdb.py", line 368, in run

   345     exec cmd in globals, locals

   346   File "<string>", line 1, in <module>

   347   File "mymodule.py", line 2, in test

   348     print spam

   349 NameError: global name 'spam' is not defined

   350 \end{lstlisting}

   351 \end{frame}

   352 

   353 \begin{frame}[fragile]

   354 \frametitle{Debugging in IPython}

   355 \small

   356 \begin{lstlisting}

   357 In [1]: %pdb

   358 Automatic pdb calling has been turned ON

   359 In [2]: import mymodule

   360 In [3]: mymodule.test()

   361 ----------------------------------------------

   362 NameError    Traceback (most recent call last)

   363 /media/python/iitb/workshops/day1/<ipython console> in <module>()

   364 /media/python/iitb/workshops/day1/mymodule.pyc in test()

   365       1 def test():

   366 ----> 2     print spam

   367 NameError: global name 'spam' is not defined

   368 > /media/python/iitb/workshops/day1/mymodule.py(2)test()

   369       0     print spam

   370 ipdb>

   371 \end{lstlisting}

   372 \end{frame}

   373 

   374 \begin{frame}[fragile]

   375 \frametitle{Debugging: Exercise}

   376 \end{frame}

   377 

   378 \end{document}