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}

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

    15 \mode<presentation>

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    22 \usepackage[english]{babel}

    23 \usepackage[latin1]{inputenc}

    24 %\usepackage{times}

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    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}

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    42 \usepackage{pgf}

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    44 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    45 % Macros

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    49       {#1}

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

    55 

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

    57 

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

    59 

    60 %%% This is from Fernando's setup.

    61 % \usepackage{color}

    62 % \definecolor{orange}{cmyk}{0,0.4,0.8,0.2}

    63 % % Use and configure listings package for nicely formatted code

    64 % \usepackage{listings}

    65 % \lstset{

    66 %    language=Python,

    67 %    basicstyle=\small\ttfamily,

    68 %    commentstyle=\ttfamily\color{blue},

    69 %    stringstyle=\ttfamily\color{orange},

    70 %    showstringspaces=false,

    71 %    breaklines=true,

    72 %    postbreak = \space\dots

    73 % }

    74 

    75 

    76 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    77 % Title page

    78 \title[Basic Python]{Python:\\Advanced Python data structures, Functions and Debugging}

    79 

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

    81 

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

    83 \date[] {10, October 2009\\Day 1, Session 4}

    84 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

    85 

    86 %\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}

    87 %\logo{\pgfuseimage{iitmlogo}}

    88 

    89 

    90 %% Delete this, if you do not want the table of contents to pop up at

    91 %% the beginning of each subsection:

    92 \AtBeginSection[]

    93 {

    94   \begin{frame}<beamer>

    95     \frametitle{Outline}

    96     \tableofcontents[currentsection,subsections]

    97   \end{frame}

    98 }

    99 

   100 

   101 % If you wish to uncover everything in a step-wise fashion, uncomment

   102 % the following command: 

   103 %\beamerdefaultoverlayspecification{<+->}

   104 

   105 %\includeonlyframes{current,current1,current2,current3,current4,current5,current6}

   106 

   107 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   108 % DOCUMENT STARTS

   109 \begin{document}

   110 

   111 \begin{frame}

   112   \titlepage

   113 \end{frame}

   114 

   115 \section{Advanced Data structures}

   116 

   117 \subsection{Dictionary}

   118 \begin{frame}{Dictionary}

   119   \begin{itemize}

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

   121     \item dictionaries index using strings

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

   123     \item \typ{d[``Terminator''] => ``I'll be back''}

   124     \item aka associative array, key-value pair, hashmap, hashtable \ldots    

   125     \item what can be keys?

   126   \end{itemize}

   127 \end{frame}

   128 

   129 \begin{frame}{Dictionary \ldots }

   130   \begin{itemize}

   131     \item \alert{Unordered}

   132       \begin{block}{Standard usage}

   133         for key in dict:\\

   134         \ \ \ \ print dict[key]

   135       \end{block}

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

   137     \item can we have duplicate keys?

   138   \end{itemize}

   139   \inctime{5}

   140 \end{frame}

   141 

   142 \begin{frame} {Problem Set 6.1}

   143   \begin{description}

   144 \item[6.1.1] 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.

   145     \item[6.1.2] Count word frequencies in a file.

   146     \item[6.1.3] Find the most used Python keywords in your Python code (import keyword).

   147 \end{description}

   148 

   149 \inctime{10}

   150 \end{frame}

   151 

   152 \subsection{Set}

   153 \begin{frame}[fragile]

   154   \frametitle{Set}

   155     \begin{itemize}

   156       \item Simplest container, mutable

   157       \item No ordering, no duplicates

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

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

   160     \end{itemize}

   161     \begin{lstlisting}

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

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

   164 >>> f10|p10

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

   166 >>> f10&p10

   167 set([2, 3, 5])

   168 >>> f10-p10

   169 set([8, 1])

   170 \end{lstlisting}

   171 \end{frame}

   172 

   173 \begin{frame}[fragile]

   174   \frametitle{Set}

   175     \begin{lstlisting}

   176 >>> p10-f10, f10^p10

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

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

   179 True

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

   181 True

   182 >>> 2 in p10

   183 True

   184 >>> 4 in p10

   185 False

   186 >>> len(f10)

   187 5

   188 \end{lstlisting}

   189 \inctime{5}

   190 \end{frame}

   191 

   192 \begin{frame}

   193   \frametitle{Problem set 6.2}

   194   \begin{description}

   195     \item[6.2.1] Given a dictionary of the names of students and their marks, identify how many duplicate marks are there? and what are these?

   196     \item[6.2.2] Given a string of the form ``4-7, 9, 12, 15'' find the numbers missing in this list for a given range.

   197 \end{description}

   198 \inctime{10}

   199 \end{frame}

   200 

   201 

   202 \section{Functions Reloaded!}

   203 \begin{frame}[fragile]

   204     \frametitle{Advanced functions}

   205     \begin{itemize}

   206         \item default args

   207         \item var args

   208         \item keyword args

   209         \item scope

   210         \item \typ{global}

   211       \end{itemize}

   212 \end{frame}

   213 

   214 \subsection{Default arguments}

   215 \begin{frame}[fragile]

   216   \frametitle{Functions: default arguments}

   217   \small

   218   \begin{lstlisting}

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

   220     while True:

   221         ok = raw_input(prompt)

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

   223             return True

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

   225                   'nope'): 

   226             return False

   227         print complaint

   228 

   229 ask_ok('?')

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

   231   \end{lstlisting}

   232 \end{frame}

   233 

   234 \subsection{Keyword arguments}

   235 \begin{frame}[fragile]

   236   \frametitle{Functions: keyword arguments}

   237   \small

   238   \begin{lstlisting}

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

   240     while True:

   241         ok = raw_input(prompt)

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

   243             return True

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

   245                   'nope'): 

   246             return False

   247         print complaint

   248 

   249 ask_ok(prompt='?')

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

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

   252 \end{lstlisting}

   253 \inctime{15} 

   254 \end{frame}

   255 

   256 \section{Functional programming}

   257 \begin{frame}[fragile]

   258     \frametitle{Functional programming}

   259     \begin{itemize}

   260       \item What is the basic idea?

   261       \item Why is it interesting?

   262       \item \typ{map, reduce, filter}

   263       \item list comprehension

   264       \item generators

   265     \end{itemize}

   266 \end{frame}

   267 

   268 \subsection{List comprehensions}

   269 \begin{frame}[fragile]

   270     \frametitle{List Comprehensions}

   271 Lets say we want to squares of all the numbers from 1 to 100

   272     \begin{lstlisting}

   273 squares = []

   274 for i in range(1, 100):

   275     squares.append(i * i)

   276     \end{lstlisting}

   277     \begin{lstlisting}

   278 # list comprehension

   279 squares = [i*i for i in range(1, 100)]

   280      \end{lstlisting}

   281 Which is more readable?

   282 \end{frame}

   283 

   284 \begin{frame}[fragile]

   285     \frametitle{List Comprehensions}

   286 What if you had a more complex function?

   287 Lets say we want squares of numbers from 1 to 100 ending in 1, 2, 5, 7 only

   288     \begin{lstlisting}

   289 squares = []

   290 for i in range(1, 100):

   291     if i % 10 in [1, 2, 5, 7]:

   292         squares.append(i * i)

   293     \end{lstlisting}

   294     \begin{lstlisting}

   295 # list comprehension

   296 squares = [i*i for i in range(1, 100)

   297            if i % 10 in [1, 2, 5, 7]]

   298      \end{lstlisting}

   299 Which is more readable?

   300 \inctime{15}

   301 \end{frame}

   302 

   303 \section{Debugging}

   304 \subsection{Errors and Exceptions}

   305 \begin{frame}[fragile]

   306  \frametitle{Errors}

   307  \begin{lstlisting}

   308 >>> while True print 'Hello world'

   309  \end{lstlisting}

   310 \pause

   311   \begin{lstlisting}

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

   313     while True print 'Hello world'

   314                    ^

   315 SyntaxError: invalid syntax

   316 \end{lstlisting}

   317 \end{frame}

   318 

   319 \begin{frame}[fragile]

   320  \frametitle{Exceptions}

   321  \begin{lstlisting}

   322 >>> print spam

   323 \end{lstlisting}

   324 \pause

   325 \begin{lstlisting}

   326 Traceback (most recent call last):

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

   328 NameError: name 'spam' is not defined

   329 \end{lstlisting}

   330 \end{frame}

   331 

   332 \begin{frame}[fragile]

   333  \frametitle{Exceptions}

   334  \begin{lstlisting}

   335 >>> 1 / 0

   336 \end{lstlisting}

   337 \pause

   338 \begin{lstlisting}

   339 Traceback (most recent call last):

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

   341 ZeroDivisionError: integer division 

   342 or modulo by zero

   343 \end{lstlisting}

   344 \end{frame}

   345 

   346 \subsection{Strategy}

   347 \begin{frame}[fragile]

   348     \frametitle{Debugging effectively}

   349     \begin{itemize}

   350         \item \kwrd{print} based strategy

   351         \item Process:

   352     \end{itemize}

   353 \pgfimage[interpolate=true,width=5cm,height=5cm]{DebugginDiagram.png}

   354 \end{frame}

   355 

   356 \begin{frame}[fragile]

   357     \frametitle{Debugging effectively}

   358     \begin{itemize}

   359       \item Using \typ{\%debug} in IPython

   360     \end{itemize}

   361 \end{frame}

   362 

   363 \begin{frame}[fragile]

   364 \frametitle{Debugging in IPython}

   365 \small

   366 \begin{lstlisting}

   367 In [1]: import mymodule

   368 In [2]: mymodule.test()

   369 ---------------------------------------------

   370 NameError   Traceback (most recent call last)

   371 <ipython console> in <module>()

   372 mymodule.py in test()

   373       1 def test():

   374 ----> 2     print spam

   375 NameError: global name 'spam' is not defined

   376 

   377 In [3]: %debug

   378 > mymodule.py(2)test()

   379       0     print spam

   380 ipdb> 

   381 \end{lstlisting}

   382 \inctime{15} 

   383 \end{frame}

   384 

   385 \subsection{Exercise}

   386 \begin{frame}[fragile]

   387 \frametitle{Debugging: Exercise}

   388 \small

   389 \begin{lstlisting}

   390 import keyword

   391 f = open('/path/to/file')

   392 

   393 freq = {}

   394 for line in f:

   395     words = line.split()

   396     for word in words:

   397         key = word.strip(',.!;?()[]: ')

   398         if keyword.iskeyword(key):

   399             value = freq[key]

   400             freq[key] = value + 1

   401 

   402 print freq

   403 \end{lstlisting}

   404 \inctime{10}

   405 \end{frame}

   406 

   407 \begin{frame}

   408   \frametitle{What did we learn?}

   409   \begin{itemize}

   410     \item Dictionaries

   411     \item Sets

   412     \item Default and keyword arguments

   413     \item Functional Programming, list comprehensions

   414     \item Errors and Exceptions in Python

   415     \item Debugging: \%debug in IPython

   416   \end{itemize}

   417 \end{frame}

   418 \end{document}