+
−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
−%Tutorial slides on Python.
+
−%
+
−% Author: FOSSEE 
+
−% Copyright (c) 2009, FOSSEE, IIT Bombay
+
−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
−
+
−\documentclass[14pt,compress]{beamer}
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−%\documentclass[draft]{beamer}
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−%\documentclass[compress,handout]{beamer}
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−%\usepackage{pgfpages} 
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−%\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]
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−
+
−% Modified from: generic-ornate-15min-45min.de.tex
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−\mode<presentation>
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−{
+
−  \usetheme{Warsaw}
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−  \useoutertheme{infolines}
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−  \setbeamercovered{transparent}
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−}
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−
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−\usepackage[english]{babel}
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−\usepackage[latin1]{inputenc}
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−%\usepackage{times}
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−\usepackage[T1]{fontenc}
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−
+
−% Taken from Fernando's slides.
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−\usepackage{ae,aecompl}
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−\usepackage{mathpazo,courier,euler}
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−\usepackage[scaled=.95]{helvet}
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−
+
−\definecolor{darkgreen}{rgb}{0,0.5,0}
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−
+
−\usepackage{listings}
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−\lstset{language=Python,
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−    basicstyle=\ttfamily\bfseries,
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−    commentstyle=\color{red}\itshape,
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−  stringstyle=\color{darkgreen},
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−  showstringspaces=false,
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−  keywordstyle=\color{blue}\bfseries}
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−
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−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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−% Macros
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−\setbeamercolor{emphbar}{bg=blue!20, fg=black}
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−\newcommand{\emphbar}[1]
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−{\begin{beamercolorbox}[rounded=true]{emphbar} 
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−      {#1}
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− \end{beamercolorbox}
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−}
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−\newcounter{time}
+
−\setcounter{time}{0}
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−\newcommand{\inctime}[1]{\addtocounter{time}{#1}{\tiny \thetime\ m}}
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−
+
−\newcommand{\typ}[1]{\lstinline{#1}}
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−
+
−\newcommand{\kwrd}[1]{ \texttt{\textbf{\color{blue}{#1}}}  }
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−
+
−%%% This is from Fernando's setup.
+
−% \usepackage{color}
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−% \definecolor{orange}{cmyk}{0,0.4,0.8,0.2}
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−% % Use and configure listings package for nicely formatted code
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−% \usepackage{listings}
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−% \lstset{
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−%    language=Python,
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−%    basicstyle=\small\ttfamily,
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−%    commentstyle=\ttfamily\color{blue},
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−%    stringstyle=\ttfamily\color{orange},
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−%    showstringspaces=false,
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−%    breaklines=true,
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−%    postbreak = \space\dots
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−% }
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−
+
−
+
−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
−% Title page
+
−\title[Basic Python]{Python language: Data structures and functions}
+
−
+
−\author[FOSSEE Team] {The FOSSEE Group}
+
−
+
−\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
+
−\date[] {8 November, 2009\\Day 2, Session 2}
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−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
−
+
−%\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}
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−%\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}<beamer>
+
−    \frametitle{Outline}
+
−    \tableofcontents[currentsection,currentsubsection]
+
−  \end{frame}
+
−}
+
−
+
−\AtBeginSection[]
+
−{
+
−  \begin{frame}<beamer>
+
−    \frametitle{Outline}
+
−    \tableofcontents[currentsection,currentsubsection]
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−  \end{frame}
+
−}
+
−
+
−% If you wish to uncover everything in a step-wise fashion, uncomment
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−% the following command: 
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−%\beamerdefaultoverlayspecification{<+->}
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−
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−%\includeonlyframes{current,current1,current2,current3,current4,current5,current6}
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−
+
−%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
−% DOCUMENT STARTS
+
−\begin{document}
+
−
+
−\begin{frame}
+
−  \titlepage
+
−\end{frame}
+
−
+
−\begin{frame}
+
−  \frametitle{Outline}
+
−  \tableofcontents
+
−  % You might wish to add the option [pausesections]
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−\end{frame}
+
−
+
−\section{Control flow}
+
−\subsection{Basic Looping}
+
−\begin{frame}[fragile]
+
−  \frametitle{\typ{while}}
+
−\begin{block}{Example: Fibonacci series}
+
−  Sum of previous two elements defines the next
+
−\end{block}
+
−  \begin{lstlisting}
+
−In []: a, b = 0, 1
+
−In []: while b < 10:
+
−  ...:     print b,
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−  ...:     a, b = b, a + b
+
−  ...:
+
−  ...:
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−\end{lstlisting}
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−\typ{1 1 2 3 5 8}\\
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−\frametitle{\typ{range()}}
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−\kwrd{range([start,] stop[, step])}\\
+
−\begin{itemize}
+
−  \item \typ{range()} returns a list of integers
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−  \item The \typ{start} and the \typ{step} arguments are optional
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−  \item \typ{stop} is not included in the list
+
−\end{itemize}
+
−\vspace*{.5in}
+
−\begin{block}{Documentation convention}
+
−  \begin{itemize}
+
−    \item \alert{Anything within \typ{[]} is optional}
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−    \begin{itemize}
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−      \item Nothing to do with Python.
+
−    \end{itemize}
+
−  \end{itemize}
+
−\end{block}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{\texttt{for} \ldots \typ{range()}}
+
−Example: print squares of first \typ{5} numbers
+
−  \begin{lstlisting}
+
−In []: for i in range(5):
+
− ....:     print i, i * i
+
− ....:
+
− ....:
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−0 0
+
−1 1
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−2 4
+
−3 9
+
−4 16
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{\texttt{for} \ldots \typ{range()}}
+
−Example: print squares of odd numbers from 3 to 9
+
−  \begin{lstlisting}
+
−In []: for i in range(3, 10, 2):
+
− ....:     print i, i * i
+
− ....:
+
− ....:
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−3 9
+
−5 25
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−7 49
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−9 81
+
−\end{lstlisting}
+
−\inctime{5}
+
−\end{frame}
+
−
+
−\subsection{Exercises}
+
−
+
−\begin{frame}{Problem set 1: Problem 1.1}
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−  Write a program that displays all three digit numbers that are equal to the sum of the cubes of their digits. That is, print numbers $abc$ that have the property $abc = a^3 + b^3 + c^3$\\
+
−\vspace*{0.2in}
+
−\emphbar{These are called $Armstrong$ numbers.}
+
−\end{frame}
+
−
+
−\begin{frame}{Problem 1.2 - Collatz sequence}
+
−\begin{enumerate}
+
−  \item Start with an arbitrary (positive) integer. 
+
−  \item If the number is even, divide by 2; if the number is odd, multiply by 3 and add 1.
+
−  \item Repeat the procedure with the new number.
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−  \item It appears that for all starting values there is a cycle of 4, 2, 1 at which the procedure loops.
+
−\end{enumerate}
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−    Write a program that accepts the starting value and prints out the Collatz sequence.
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]{Problem 1.3}
+
−  Write a program that prints the following pyramid on the screen. 
+
−  \begin{lstlisting}
+
−1
+
−2  2
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−3  3  3
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−4  4  4  4
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−  \end{lstlisting}
+
−The number of lines must be obtained from the user.\\
+
−\pause
+
−\emphbar{When can your code fail?}
+
−\inctime{5}
+
−\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]
+
−  \end{lstlisting}
+
−\centerline{is a list}
+
−\end{block}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Lists: methods}
+
−  \begin{lstlisting}
+
−In []: num = [1, 2, 3, 4]
+
−
+
−In []: num + [9, 10, 11]
+
−Out[]: [1, 2, 3, 4, 9, 10, 11]
+
−
+
−In []: num.append([9, 10, 11])
+
−
+
−In []: num
+
−Out[]: [1, 2, 3, 4, [9, 10, 11]]
+
−  \end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Lists: methods}
+
−  \begin{lstlisting}
+
−In []: num = [1, 2, 3, 4]
+
−
+
−In []: num.extend([5, 6, 7])
+
−In []: num
+
−Out[]: [1, 2, 3, 4, 5, 6, 7]
+
−
+
−In []: num.reverse()
+
−In []: num
+
−Out[]: [7, 6, 5, 4, 3, 2, 1]
+
−
+
−In []: num.remove(6)
+
−In []: num
+
−  \end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Lists: slicing}
+
−  \begin{itemize}
+
−    \item \typ{list[initial:final]}
+
−  \end{itemize}
+
−\begin{lstlisting}
+
−In []: a = [1, 2, 3, 4, 5]
+
−
+
−In []: a[1:3]
+
−Out[]: [2, 3]
+
−
+
−In []: a[1:-1]
+
−Out[]: [2, 3, 4]
+
−
+
−In []: a[:3]
+
−Out[]: [1, 2, 3]
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Lists: slicing}
+
−  \begin{itemize}
+
−    \item \typ{list[initial:final:step]}
+
−  \end{itemize}
+
−\begin{lstlisting}
+
−In []: a[1:-1:2]
+
−Out[]: [2, 4]
+
−
+
−In []: a[::2]
+
−Out[]: [1, 3, 5]
+
−
+
−In []: a[-1::-1]
+
−Out[]: [5, 4, 3, 2, 1]
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−\frametitle{List containership}
+
−\begin{lstlisting}
+
−In []: 4 in num
+
−Out[]: True
+
−
+
−In []: b = 15
+
−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
+
−
+
−In []: t[4] = 7 
+
−\end{lstlisting}
+
−\pause
+
−\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 $\Rightarrow$ overwritten!\\
+
−    You can iterate through a dictionary using keys.
+
−  \end{block}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Dictionaries: containership}
+
−  \begin{lstlisting}
+
−In []: 'Inn' in player
+
−Out[]: True
+
−
+
−In []: 'Econ' in player
+
−Out[]: False
+
−  \end{lstlisting}
+
−  \begin{block}{Note}
+
−    \begin{itemize}
+
−      \item We can check for the containership of keys only
+
−      \item Not values
+
−    \end{itemize}
+
−  \end{block}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Dictionaries: methods}
+
−  \begin{lstlisting}
+
−In []: player.keys()
+
−Out[]: ['Runs', 'Inn', 'Avg', 'Mat']
+
−
+
−In []: player.values()
+
−Out[]: [10823, 233, 
+
−        52.530000000000001, 134]
+
−  \end{lstlisting}
+
−\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{Sets}
+
−\begin{frame}[fragile]
+
−  \frametitle{Sets}
+
−    \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}
+
−
+
−In []: f10 = set([1,2,3,5,8])
+
−
+
−In []: p10 = set([2,3,5,7])
+
−
+
−In []: f10 | p10
+
−Out[]: set([1, 2, 3, 5, 7, 8])
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Set \ldots}
+
−    \begin{lstlisting}
+
−In []: f10 & p10
+
−Out[]: set([2, 3, 5])
+
−
+
−In []: f10 - p10
+
−Out[]: set([1, 8])
+
−
+
−In []: p10 - f10, f10 ^ p10
+
−Out[]: (set([7]), set([1, 7, 8]))
+
−
+
−In []: set([2,3]) < p10
+
−Out[]: True
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle{Set \ldots}
+
−    \begin{lstlisting}
+
−In []: set([2,3]) <= p10
+
−Out[]: True
+
−
+
−In []: 2 in p10
+
−Out[]: True
+
−
+
−In []: 4 in p10
+
−Out[]: False
+
−
+
−In []: len(f10)
+
−Out[]: 5
+
−\end{lstlisting}
+
−\end{frame}
+
−
+
−\begin{frame}
+
−  \frametitle{Problem set 2.2: Problem 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?
+
−\end{frame}
+
−
+
−\begin{frame}
+
−  \frametitle{Problem 2.2.2}
+
−Given a list of words, find all the anagrams in the list.
+
−
+
−\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 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}
+
−  \emphbar{Note docstrings}
+
−\end{frame}
+
−
+
−\begin{frame}[fragile]
+
−  \frametitle {What does this function do?}
+
−  \begin{lstlisting}
+
−def what( n ):
+
−    if n < 0: n = -n
+
−    while n > 0:
+
−        if n % 2 == 1:
+
−            return False
+
−        n /= 10
+
−    return True
+
−  \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}
+
−
+
−\begin{frame}
+
−  \frametitle{What did we learn?}
+
−  \begin{itemize}
+
−    \item Loops: \kwrd{while}, \kwrd{for}
+
−    \item Advanced Data structures:
+
−    \begin{itemize}
+
−      \item Lists
+
−      \item Tuples
+
−      \item Dictionaries
+
−      \item Sets
+
−    \end{itemize}
+
−    \item Functions
+
−    \item Docstrings
+
−  \end{itemize}
+
−\end{frame}
+
−
+
−\end{document}