# HG changeset patch # User Anoop Jacob Thomas # Date 1286823301 -19800 # Node ID d98f554bbec0d4ea065846a292f65d66cea0115d # Parent a130a1f494c3be1344045fda11cefeaa8b6777e9 added slides for getting-started-with-arrays. diff -r a130a1f494c3 -r d98f554bbec0 getting-started-with-arrays/script.rst --- a/getting-started-with-arrays/script.rst Mon Oct 11 23:03:49 2010 +0530 +++ b/getting-started-with-arrays/script.rst Tue Oct 12 00:25:01 2010 +0530 @@ -71,6 +71,8 @@ here and try to do it yourself, try ``ar.tab`` and find a suitable method for that. +{{{ switch to next slide, reshape() method }}} + We can use the function ``reshape()`` for that purpose and it can be done as, :: @@ -79,6 +81,8 @@ ar.reshape(4,2) ar = ar.reshape(2,4) +{{{ switch to next slide, creating array from list}}} + Now, let us see how to convert a list object to an array. As you have already seen, in both of the previous statements we have passed a list, so creating an array can be done so, first let us create a list @@ -110,7 +114,7 @@ {{{ switch to the next slide, unsolved exercise 2 }}} -Find out the shape of the other two arrays that we have created. +Find out the shape of the other arrays that we have created. {{{ Array can have only a single type of data }}} @@ -129,6 +133,8 @@ Did you notice it, +{{{ switch to next slide, implicit type casting }}} + {{{ highlight all the array elements one by one using mouse movements }}} @@ -226,7 +232,7 @@ Returns an array with element by element multiplication, notice that it does not perform matrix multiplication. -{{{ switch to next slide, recap slide }}} +{{{ switch to next slide, summary slide }}} So this brings us to the end of this tutorial, in this tutorial we covered basics of arrays, how to create an array, converting a list to diff -r a130a1f494c3 -r d98f554bbec0 getting-started-with-arrays/slides.org --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/getting-started-with-arrays/slides.org Tue Oct 12 00:25:01 2010 +0530 @@ -0,0 +1,132 @@ +#+LaTeX_CLASS: beamer +#+LaTeX_CLASS_OPTIONS: [presentation] +#+BEAMER_FRAME_LEVEL: 1 + +#+BEAMER_HEADER_EXTRA: \usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent} +#+COLUMNS: %45ITEM %10BEAMER_env(Env) %10BEAMER_envargs(Env Args) %4BEAMER_col(Col) %8BEAMER_extra(Extra) +#+PROPERTY: BEAMER_col_ALL 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 :ETC + +#+LaTeX_CLASS: beamer +#+LaTeX_CLASS_OPTIONS: [presentation] + +#+LaTeX_HEADER: \usepackage[english]{babel} \usepackage{ae,aecompl} +#+LaTeX_HEADER: \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet} + +#+LaTeX_HEADER: \usepackage{listings} + +#+LaTeX_HEADER:\lstset{language=Python, basicstyle=\ttfamily\bfseries, +#+LaTeX_HEADER: commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen}, +#+LaTeX_HEADER: showstringspaces=false, keywordstyle=\color{blue}\bfseries} + +#+TITLE: Getting started with arrays +#+AUTHOR: FOSSEE +#+EMAIL: info@fossee.in +#+DATE: + +#+DESCRIPTION: +#+KEYWORDS: +#+LANGUAGE: en +#+OPTIONS: H:3 num:nil toc:nil \n:nil @:t ::t |:t ^:t -:t f:t *:t <:t +#+OPTIONS: TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc + +* Outline + - Arrays + - why arrays over lists + - Creating arrays + - Array operations + +* Overview of Arrays + - Arrays are homogeneous data structures. + - elements have to the same data type + - Arrays are faster compared to lists + - at least /80-100 times/ faster than lists + +* Creating Arrays + - Creating a 1-dimensional array + : In []: a1 = array([1, 2, 3, 4]) + - Creating a 2-dimensional array + : In []: a2 = array([[1,2,3,4],[5,6,7,8]]) + - Easier method of creating array with consecutive elements. + : In []: ar = arange(1,9) +* ~reshape()~ method + - To reshape an array + : In []: ar.reshape(2, 4) + : In []: ar.reshape(4, 2) + : In []: ar = ar.reshape(2, 4) + +* Creating ~array~ from ~list~. + - ~array()~ method accepts list as argument + - Creating a list + : In []: l1 = [1, 2, 3, 4] + - Creating an array + : In []: a3 = array(l1) + +* Exercise 1 + Create a 3-dimensional array of the order (2, 2, 4). + +* ~.shape~ of array + - ~.shape~ + To find the shape of the array + : In []: a1.shape + - ~.shape~ + returns a tuple of shape +* Exercise 2 + Find out the shape of the other arrays(a2, a3, ar) that we have created. +* Homogeneous data + - All elements in array should be of same type + : In []: a4 = array([1,2,3,'a string']) +* Implicit type casting + : In []: a4 + All elements are type casted to string type +* ~identity()~, ~zeros()~ methods + - ~identity(n)~ + Creates an identity matrix, a square matrix of order (n, n) with diagonal elements 1 and others 0. + - ~zeros((m, n))~ + Creates an ~m X n~ matrix with all elements 0. + +* Learning exercise + - Find out about + - ~zeros_like()~ + - ~ones()~ + - ~ones_like()~ + +* Array operations + - ~a1 * 2~ + returns a new array with all elements of ~a1~ multiplied by ~2~. + - Similarly ~+~, ~-~ \& ~/~. + - ~a1 + 2~ + returns a new array with all elements of ~a1~ summed with ~2~. + - ~a1 += 2~ + adds ~2~ to all elements of array ~a1~. + - Similarly ~-=~, ~*=~ \& ~/=~. + - ~a1 + a2~ + does elements-wise addition. + - Similarly ~-~, ~*~ \& ~/~. + - ~a1 * a2~ + does element-wise multiplication + + *Note* - array(A) * array(B) does element wise multiplication and not matrix multiplication + +* Summary + In this tutorial we covered, + - Basics of arrays + - Creating arrays + - Arrays from lists + - Basic array operations + +* Thank you! +#+begin_latex + \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_latex + + diff -r a130a1f494c3 -r d98f554bbec0 getting-started-with-arrays/slides.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/getting-started-with-arrays/slides.tex Tue Oct 12 00:25:01 2010 +0530 @@ -0,0 +1,277 @@ +% Created 2010-10-12 Tue 00:20 +\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{Getting started with arrays} +\author{FOSSEE} +\date{} + +\usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent} +\begin{document} + +\maketitle + + + + + + + + + +\begin{frame} +\frametitle{Outline} +\label{sec-1} + +\begin{itemize} +\item Arrays + +\begin{itemize} +\item why arrays over lists +\end{itemize} + +\item Creating arrays +\item Array operations +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Overview of Arrays} +\label{sec-2} + +\begin{itemize} +\item Arrays are homogeneous data structures. + +\begin{itemize} +\item elements have to the same data type +\end{itemize} + +\item Arrays are faster compared to lists + +\begin{itemize} +\item at least \emph{80-100 times} faster than lists +\end{itemize} + +\end{itemize} +\end{frame} +\begin{frame}[fragile] +\frametitle{Creating Arrays} +\label{sec-3} + +\begin{itemize} +\item Creating a 1-dimensional array +\end{itemize} + +\begin{verbatim} + In []: a1 = array([1, 2, 3, 4]) +\end{verbatim} + +\begin{itemize} +\item Creating a 2-dimensional array +\end{itemize} + +\begin{verbatim} + In []: a2 = array([[1,2,3,4],[5,6,7,8]]) +\end{verbatim} + +\begin{itemize} +\item Easier method of creating array with consecutive elements. +\end{itemize} + +\begin{verbatim} + In []: ar = arange(1,9) +\end{verbatim} +\end{frame} +\begin{frame}[fragile] +\frametitle{\texttt{reshape()} method} +\label{sec-4} + +\begin{itemize} +\item To reshape an array +\end{itemize} + +\begin{verbatim} + In []: ar.reshape(2, 4) + In []: ar.reshape(4, 2) + In []: ar = ar.reshape(2, 4) +\end{verbatim} +\end{frame} +\begin{frame}[fragile] +\frametitle{Creating \texttt{array} from \texttt{list}.} +\label{sec-5} + +\begin{itemize} +\item \texttt{array()} method accepts list as argument +\item Creating a list +\begin{verbatim} + In []: l1 = [1, 2, 3, 4] +\end{verbatim} + +\item Creating an array +\begin{verbatim} + In []: a3 = array(l1) +\end{verbatim} + +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Exercise 1} +\label{sec-6} + + Create a 3-dimensional array of the order (2, 2, 4). +\end{frame} +\begin{frame}[fragile] +\frametitle{\texttt{.shape} of array} +\label{sec-7} + +\begin{itemize} +\item \texttt{.shape} + To find the shape of the array +\begin{verbatim} + In []: a1.shape +\end{verbatim} + +\item \texttt{.shape} + returns a tuple of shape +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Exercise 2} +\label{sec-8} + + Find out the shape of the other arrays(a2, a3, ar) that we have created. +\end{frame} +\begin{frame}[fragile] +\frametitle{Homogeneous data} +\label{sec-9} + +\begin{itemize} +\item All elements in array should be of same type +\begin{verbatim} + In []: a4 = array([1,2,3,'a string']) +\end{verbatim} + +\end{itemize} +\end{frame} +\begin{frame}[fragile] +\frametitle{Implicit type casting} +\label{sec-10} + +\begin{verbatim} + In []: a4 +\end{verbatim} + + All elements are type casted to string type +\end{frame} +\begin{frame} +\frametitle{\texttt{identity()}, \texttt{zeros()} methods} +\label{sec-11} + +\begin{itemize} +\item \texttt{identity(n)} + Creates an identity matrix, a square matrix of order (n, n) with diagonal elements 1 and others 0. +\item \texttt{zeros((m, n))} + Creates an \texttt{m X n} matrix with all elements 0. +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Learning exercise} +\label{sec-12} + +\begin{itemize} +\item Find out about + +\begin{itemize} +\item \texttt{zeros\_like()} +\item \texttt{ones()} +\item \texttt{ones\_like()} +\end{itemize} + +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Array operations} +\label{sec-13} + +\begin{itemize} +\item \texttt{a1 * 2} + returns a new array with all elements of \texttt{a1} multiplied by \texttt{2}. + +\begin{itemize} +\item Similarly \texttt{+}, \texttt{-} \& \texttt{/}. +\end{itemize} + +\item \texttt{a1 + 2} + returns a new array with all elements of \texttt{a1} summed with \texttt{2}. +\item \texttt{a1 += 2} + adds \texttt{2} to all elements of array \texttt{a1}. + +\begin{itemize} +\item Similarly \texttt{-=}, \texttt{*=} \& \texttt{/=}. +\end{itemize} + +\item \texttt{a1 + a2} + does elements-wise addition. + +\begin{itemize} +\item Similarly \texttt{-}, \texttt{*} \& \texttt{/}. +\end{itemize} + +\item \texttt{a1 * a2} + does element-wise multiplication +\end{itemize} + + + \textbf{Note} - array(A) * array(B) does element wise multiplication and not matrix multiplication +\end{frame} +\begin{frame} +\frametitle{Summary} +\label{sec-14} + + In this tutorial we covered, +\begin{itemize} +\item Basics of arrays +\item Creating arrays +\item Arrays from lists +\item Basic array operations +\end{itemize} +\end{frame} +\begin{frame} +\frametitle{Thank you!} +\label{sec-15} + + \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}