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% Created 2010-10-11 Mon 23:02
\documentclass[presentation]{beamer}
\usepackage[latin1]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{fixltx2e}
\usepackage{graphicx}
\usepackage{longtable}
\usepackage{float}
\usepackage{wrapfig}
\usepackage{soul}
\usepackage{t1enc}
\usepackage{textcomp}
\usepackage{marvosym}
\usepackage{wasysym}
\usepackage{latexsym}
\usepackage{amssymb}
\usepackage{hyperref}
\tolerance=1000
\usepackage[english]{babel} \usepackage{ae,aecompl}
\usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet}
\usepackage{listings}
\lstset{language=Python, basicstyle=\ttfamily\bfseries,
commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen},
showstringspaces=false, keywordstyle=\color{blue}\bfseries}
\providecommand{\alert}[1]{\textbf{#1}}
\title{Dictionaries}
\author{FOSSEE}
\date{}
\usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent}
\begin{document}
\maketitle
\begin{frame}
\frametitle{Outline}
\label{sec-1}
\begin{itemize}
\item Creating dictionaries
\begin{itemize}
\item empty dictionaries
\item with data
\end{itemize}
\item Keys and values
\item Checking for elements
\item Iterating over elements
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Overview of Dictionaries}
\label{sec-2}
\begin{itemize}
\item A dictionary contains meaning of words
\begin{itemize}
\item \emph{Word} is the \emph{key} here.
\item \emph{Meaning} is the \emph{value} here.
\end{itemize}
\item A Key-Value pair data structure
\begin{itemize}
\item Provide key-value mappings
\end{itemize}
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{Creating dictionary}
\label{sec-3}
\begin{itemize}
\item Empty dictionary
\begin{itemize}
\item \texttt{mt\_dict = \{\}}
\begin{itemize}
\item \texttt{[]} - lists
\item \texttt{\{\}} - dictionaries
\end{itemize}
\end{itemize}
\item With data
\begin{verbatim}
extensions = {'jpg' : 'JPEG Image',
'py' : 'Python script',
'html' : 'Html document',
'pdf' : 'Portable Document Format'}
\end{verbatim}
\textbf{Note} - ordering in dictionaries cannot be relied on
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{Accessing Elements}
\label{sec-4}
\begin{itemize}
\item syntax
\begin{verbatim}
extensions[key]
\end{verbatim}
\end{itemize}
\begin{verbatim}
In []: print extensions['jpg']
Out []: JPEG Image
In []: print extensions['zip']
\end{verbatim}
\end{frame}
\begin{frame}[fragile]
\frametitle{Adding and Deleting values}
\label{sec-5}
\begin{itemize}
\item Adding a new value
\begin{verbatim}
In []: extension['cpp'] = 'C++ code'
\end{verbatim}
adds a new key \emph{cpp} with \emph{C++ code} as value
\item Deleting values
\begin{verbatim}
In []: del extensions['pdf']
\end{verbatim}
deletes the key-value pair identified by \emph{pdf}
\item Changing value associated with a key
\begin{verbatim}
In []: extension['cpp'] = 'C++ source code'
\end{verbatim}
changes the value of the existing key
\end{itemize}
\end{frame}
\begin{frame}[fragile]
\frametitle{Checking for container-ship of keys}
\label{sec-6}
\begin{verbatim}
In []: 'py' in extensions
Out []: True
\end{verbatim}
Returns \textbf{True} if the \emph{key} is found.
\begin{verbatim}
In []: 'odt' in extensions
Out []: False
\end{verbatim}
Returns \textbf{False} if the \emph{key} is not found.
\end{frame}
\begin{frame}[fragile]
\frametitle{Retrieve keys and values}
\label{sec-7}
\begin{itemize}
\item \texttt{.keys()} method
\begin{verbatim}
In []: extensions.keys()
\end{verbatim}
Returns a list of keys in the dictionary.
\item \texttt{.values()} method
\begin{verbatim}
In []: extensions.values()
\end{verbatim}
Returns the list of values in the dictionary.
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Exercise 1}
\label{sec-8}
Print the keys and values in the dictionary one by one.
\end{frame}
\begin{frame}
\frametitle{Summary}
\label{sec-9}
\begin{itemize}
\item Creating dictionaries
\begin{itemize}
\item empty dictionaries
\item with data
\end{itemize}
\item \texttt{.keys()} method
\item \texttt{.values()} method
\item Iterating over dictionaries
\end{itemize}
\end{frame}
\begin{frame}
\frametitle{Thank you!}
\label{sec-10}
\begin{block}{}
\begin{center}
This spoken tutorial has been produced by the
\textcolor{blue}{FOSSEE} team, which is funded by the
\end{center}
\begin{center}
\textcolor{blue}{National Mission on Education through \\
Information \& Communication Technology \\
MHRD, Govt. of India}.
\end{center}
\end{block}
\end{frame}
\end{document}
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