diff -r 88a01948450d -r d33698326409 getting-started-with-arrays/slides.org --- a/getting-started-with-arrays/slides.org Wed Nov 17 23:24:57 2010 +0530 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,135 +0,0 @@ -#+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]) - ~[1, 2, 3, 4]~ is a list. -* Creating two-dimensional array - - Creating a 2-dimensional array - : In []: a2 = array([[1,2,3,4],[5,6,7,8]]) - here we convert a list of lists to an array making a 2-d array. - - Using ~arange()~ function - : 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 []: a2.shape - - ~.shape~ - returns a tuple of shape -* Exercise 2 - Find out the shape of the other arrays(a1, 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 - -