From d0a204b8c5bb49fe56e7ad9d03186c88d3b427a2 Mon Sep 17 00:00:00 2001 From: Madhusudan.C.S Date: Wed, 28 Oct 2009 15:53:33 +0530 Subject: Created and made first cut slides for session 2 day 2. --- day2/session2.tex | 522 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 522 insertions(+) create mode 100644 day2/session2.tex (limited to 'day2/session2.tex') diff --git a/day2/session2.tex b/day2/session2.tex new file mode 100644 index 0000000..5b1553d --- /dev/null +++ b/day2/session2.tex @@ -0,0 +1,522 @@ +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%Tutorial slides on Python. +% +% Author: Prabhu Ramachandran +% Copyright (c) 2005-2009, Prabhu Ramachandran +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +\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 +{ + \usetheme{Warsaw} + \useoutertheme{split} + \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]{\texttt{#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:\\A formal approach} + +\author[FOSSEE Team] {The FOSSEE Group} + +\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay} +\date[] {1, November 2009\\Day 2, Session 2} +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +%\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} + \frametitle{Outline} + \tableofcontents[currentsection,currentsubsection] + \end{frame} +} + +\AtBeginSection[] +{ + \begin{frame} + \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{Data structures} +\subsection{Lists} +\begin{frame}[fragile] + \frametitle{Lists} +\begin{block}{We already know that} + \begin{lstlisting} +num = [1, 2, 3, 4, 5, 6, 7, 8] + \end{lstlisting} +\centerline{is a list} +\end{block} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Lists: methods} + \begin{lstlisting} +In []: num.reverse() +In []: num +Out[]: [8, 7, 6, 5, 4, 3, 2, 1] + +In []: num.extend([0, -1, -2]) +In []: num +Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1] + +In []: num.remove(0) +In []: num +Out[]: [8, 7, 6, 5, 4, 3, 2, 1, -1] + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] +\frametitle{List containership} +\begin{lstlisting} +In []: a = 8 + +In []: a in num +Out[]: True + +In []: b = 10 +In []: b in num +Out[]: False + +In []: b not in num +Out[]: True +\end{lstlisting} +\end{frame} + +\subsection{Tuples} +\begin{frame}[fragile] +\frametitle{Tuples: Immutable lists} +\begin{lstlisting} +In []: t = (1, 2, 3, 4, 5, 6, 7, 8) +In []: t[0] + t[3] + t[-1] +Out[]: 13 +\end{lstlisting} +\begin{block}{Note:} +\begin{itemize} + \item Tuples are immutable - cannot be changed +\end{itemize} +\end{block} + \inctime{10} +\end{frame} + +\begin{frame} + {A classic problem} + \begin{block} + {Interchange values} + How to interchange values of two variables? + \end{block} + \pause + \begin{block}{Note:} + This Python idiom works for all types of variables.\\ +They need not be of the same type! + \end{block} +\end{frame} + +\subsection{Dictionaries} +\begin{frame}[fragile] + \frametitle{Dictionaries: Recall} + \begin{lstlisting} +In []: player = {'Mat': 134,'Inn': 233, + 'Runs': 10823, 'Avg': 52.53} + +In []: player['Avg'] +Out[]: 52.530000000000001 + \end{lstlisting} + \begin{block}{Note!} + Duplicate keys are not allowed!\\ + Dictionaries are iterable through keys. + \end{block} +\end{frame} + +\begin{frame} {Problem Set 2.1: Problem 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. +\end{frame} + +\subsection{Set} +\begin{frame}[fragile] + \frametitle{Set} + \begin{itemize} + \item Simplest container, mutable + \item No ordering, no duplicates + \item usual suspects: union, intersection, subset \ldots + \item >, >=, <, <=, in, \ldots + \end{itemize} + \begin{lstlisting} +>>> f10 = set([1,2,3,5,8]) +>>> p10 = set([2,3,5,7]) +>>> f10|p10 +set([1, 2, 3, 5, 7, 8]) +>>> f10&p10 +set([2, 3, 5]) +>>> f10-p10 +set([8, 1]) +\end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Set} + \begin{lstlisting} +>>> p10-f10, f10^p10 +set([7]), set([1, 7, 8]) +>>> set([2,3]) < p10 +True +>>> set([2,3]) <= p10 +True +>>> 2 in p10 +True +>>> 4 in p10 +False +>>> len(f10) +5 +\end{lstlisting} +\end{frame} + +\begin{frame} + \frametitle{Problem set 2.2} + \begin{description} + \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? + \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. +\end{description} +\inctime{15} +\end{frame} + +\section{Functions} +\begin{frame}[fragile] + \frametitle{Functions} + \begin{itemize} + \item \kwrd{def} - keyword to define a function + \item Arguments are local to a function + \item Docstrings are important! + \item Functions can return multiple values + \end{itemize} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Functions: example} + \begin{lstlisting} +def signum( r ): + """returns 0 if r is zero + -1 if r is negative + +1 if r is positive""" + if r < 0: + return -1 + elif r > 0: + return 1 + else: + return 0 + \end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + {What does this function do?} +\begin{lstlisting} +def what( n ): + i = 1 + while i * i < n: + i += 1 + return i * i == n, i + \end{lstlisting} +\end{frame} + +\subsection{Default arguments} +\begin{frame}[fragile] + \frametitle{Functions: default arguments} + \small + \begin{lstlisting} +def ask_ok(prompt, complaint='Yes or no!'): + while True: + ok = raw_input(prompt) + if ok in ('y', 'ye', 'yes'): + return True + if ok in ('n', 'no', 'nop', + 'nope'): + return False + print complaint + +ask_ok('?') +ask_ok('?', '[Y/N]') + \end{lstlisting} +\end{frame} + +\subsection{Built-in functions} +\begin{frame} + {Before writing a function} + \begin{itemize} + \item Variety of builtin 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] + {Modules} +\begin{lstlisting} +>>> sqrt(2) +Traceback (most recent call last): + File "", line 1, in +NameError: name 'sqrt' is not defined +>>> import math +>>> math.sqrt(2) +1.4142135623730951 +\end{lstlisting} +\end{frame} + +\begin{frame}[fragile] + {Modules} + \begin{itemize} + \item The \kwrd{import} keyword ``loads'' a module + \item One can also use: + \begin{lstlisting} +>>> from math import sqrt +>>> from math import * + \end{lstlisting} + \item What is the difference? + \item \alert{Use the latter only in interactive mode} + \end{itemize} + \emphbar{Package hierarchies} + \begin{lstlisting} +>>> from os.path import exists + \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} + +\section{Coding Style} +\begin{frame}{Readability and Consistency} + \begin{itemize} + \item Readability Counts!\\Code is read more often than its written. + \item Consistency! + \item Know when to be inconsistent. + \end{itemize} +\end{frame} + +\begin{frame}[fragile] \frametitle{A question of good style} + \begin{lstlisting} + amount = 12.68 + denom = 0.05 + nCoins = round(amount/denom) + rAmount = nCoins * denom + \end{lstlisting} + \pause + \begin{block}{Style Rule \#1} + Naming is 80\% of programming + \end{block} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Code Layout} + \begin{itemize} + \item Indentation + \item Tabs or Spaces?? + \item Maximum Line Length + \item Blank Lines + \item Encodings + \end{itemize} +\end{frame} + +\begin{frame}{Whitespaces in Expressions} + \begin{itemize} + \item When to use extraneous whitespaces?? + \item When to avoid extra whitespaces?? + \item Use one statement per line + \end{itemize} +\end{frame} + +\begin{frame}{Comments} + \begin{itemize} + \item No comments better than contradicting comments + \item Block comments + \item Inline comments + \end{itemize} +\end{frame} + +\begin{frame}{Docstrings} + \begin{itemize} + \item When to write docstrings? + \item Ending the docstrings + \item One liner docstrings + \end{itemize} +More information at PEP8: http://www.python.org/dev/peps/pep-0008/ +\inctime{5} +\end{frame} + +\section{Objects} +\begin{frame}{Objects in general} + \begin{itemize} + \item What is an Object? (Types and classes) + \item identity + \item type + \item method + \end{itemize} +\end{frame} + +\begin{frame}{Almost everything is an Object!} + \begin{itemize} + \item \typ{list} + \item \typ{tuple} + \item \typ{string} + \item \typ{dictionary} + \item \typ{function} + \item Of course, user defined class objects! + \end{itemize} +\end {frame} + +\begin{frame}{Using Objects} + \begin{itemize} + \item Creating Objects: Initialization + \item Object Manipulation: Object methods and ``.'' operator + \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 Lists, Tuples, Dictionaries, Sets: creation and manipulation + \item More about functions + \item Coding style + \item Objects: creation and manipulation + \end{itemize} +\end{frame} + +\end{document} -- cgit