1 % Created 2010-11-07 Sun 15:18 |
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2 \documentclass[presentation]{beamer} |
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3 \usepackage[latin1]{inputenc} |
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4 \usepackage[T1]{fontenc} |
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5 \usepackage{fixltx2e} |
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6 \usepackage{graphicx} |
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7 \usepackage{longtable} |
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8 \usepackage{float} |
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9 \usepackage{wrapfig} |
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10 \usepackage{soul} |
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11 \usepackage{t1enc} |
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12 \usepackage{textcomp} |
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13 \usepackage{marvosym} |
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14 \usepackage{wasysym} |
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15 \usepackage{latexsym} |
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16 \usepackage{amssymb} |
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17 \usepackage{hyperref} |
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18 \tolerance=1000 |
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19 \usepackage[english]{babel} \usepackage{ae,aecompl} |
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20 \usepackage{mathpazo,courier,euler} \usepackage[scaled=.95]{helvet} |
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21 \usepackage{listings} |
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22 \lstset{language=Python, basicstyle=\ttfamily\bfseries, |
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23 commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen}, |
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24 showstringspaces=false, keywordstyle=\color{blue}\bfseries} |
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25 \providecommand{\alert}[1]{\textbf{#1}} |
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26 |
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27 \title{Getting started with arrays} |
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28 \author{FOSSEE} |
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29 \date{} |
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30 |
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31 \usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent} |
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32 \begin{document} |
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33 |
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34 \maketitle |
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35 |
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36 |
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37 |
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38 |
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39 |
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40 |
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41 |
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42 |
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43 |
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44 \begin{frame} |
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45 \frametitle{Outline} |
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46 \label{sec-1} |
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47 |
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48 \begin{itemize} |
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49 \item Arrays |
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50 |
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51 \begin{itemize} |
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52 \item why arrays over lists |
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53 \end{itemize} |
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54 |
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55 \item Creating arrays |
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56 \item Array operations |
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57 \end{itemize} |
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58 \end{frame} |
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59 \begin{frame} |
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60 \frametitle{Overview of Arrays} |
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61 \label{sec-2} |
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62 |
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63 \begin{itemize} |
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64 \item Arrays are homogeneous data structures. |
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65 |
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66 \begin{itemize} |
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67 \item elements have to the same data type |
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68 \end{itemize} |
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69 |
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70 \item Arrays are faster compared to lists |
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71 |
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72 \begin{itemize} |
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73 \item at least \emph{80-100 times} faster than lists |
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74 \end{itemize} |
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75 |
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76 \end{itemize} |
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77 \end{frame} |
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78 \begin{frame}[fragile] |
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79 \frametitle{Creating Arrays} |
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80 \label{sec-3} |
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81 |
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82 \begin{itemize} |
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83 \item Creating a 1-dimensional array |
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84 \end{itemize} |
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85 |
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86 \begin{verbatim} |
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87 In []: a1 = array([1, 2, 3, 4]) |
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88 \end{verbatim} |
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89 |
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90 \texttt{[1, 2, 3, 4]} is a list. |
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91 \end{frame} |
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92 \begin{frame}[fragile] |
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93 \frametitle{Creating two-dimensional array} |
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94 \label{sec-4} |
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95 |
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96 \begin{itemize} |
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97 \item Creating a 2-dimensional array |
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98 \end{itemize} |
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99 |
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100 \begin{verbatim} |
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101 In []: a2 = array([[1,2,3,4],[5,6,7,8]]) |
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102 \end{verbatim} |
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103 |
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104 here we convert a list of lists to an array making a 2-d array. |
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105 \begin{itemize} |
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106 \item Easier method of creating array with consecutive elements. |
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107 \end{itemize} |
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108 |
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109 \begin{verbatim} |
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110 In []: ar = arange(1,9) |
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111 \end{verbatim} |
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112 \end{frame} |
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113 \begin{frame}[fragile] |
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114 \frametitle{\texttt{reshape()} method} |
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115 \label{sec-5} |
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116 |
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117 \begin{itemize} |
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118 \item To reshape an array |
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119 \end{itemize} |
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120 |
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121 \begin{verbatim} |
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122 In []: ar.reshape(2, 4) |
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123 In []: ar.reshape(4, 2) |
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124 In []: ar = ar.reshape(2, 4) |
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125 \end{verbatim} |
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126 \end{frame} |
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127 \begin{frame}[fragile] |
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128 \frametitle{Creating \texttt{array} from \texttt{list}.} |
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129 \label{sec-6} |
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130 |
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131 \begin{itemize} |
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132 \item \texttt{array()} method accepts list as argument |
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133 \item Creating a list |
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134 \begin{verbatim} |
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135 In []: l1 = [1, 2, 3, 4] |
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136 \end{verbatim} |
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137 |
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138 \item Creating an array |
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139 \begin{verbatim} |
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140 In []: a3 = array(l1) |
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141 \end{verbatim} |
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142 |
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143 \end{itemize} |
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144 \end{frame} |
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145 \begin{frame} |
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146 \frametitle{Exercise 1} |
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147 \label{sec-7} |
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148 |
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149 Create a 3-dimensional array of the order (2, 2, 4). |
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150 \end{frame} |
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151 \begin{frame}[fragile] |
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152 \frametitle{\texttt{.shape} of array} |
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153 \label{sec-8} |
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154 |
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155 \begin{itemize} |
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156 \item \texttt{.shape} |
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157 To find the shape of the array |
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158 \begin{verbatim} |
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159 In []: a1.shape |
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160 \end{verbatim} |
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161 |
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162 \item \texttt{.shape} |
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163 returns a tuple of shape |
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164 \end{itemize} |
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165 \end{frame} |
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166 \begin{frame} |
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167 \frametitle{Exercise 2} |
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168 \label{sec-9} |
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169 |
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170 Find out the shape of the other arrays(a2, a3, ar) that we have created. |
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171 \end{frame} |
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172 \begin{frame}[fragile] |
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173 \frametitle{Homogeneous data} |
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174 \label{sec-10} |
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175 |
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176 \begin{itemize} |
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177 \item All elements in array should be of same type |
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178 \begin{verbatim} |
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179 In []: a4 = array([1,2,3,'a string']) |
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180 \end{verbatim} |
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181 |
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182 \end{itemize} |
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183 \end{frame} |
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184 \begin{frame}[fragile] |
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185 \frametitle{Implicit type casting} |
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186 \label{sec-11} |
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187 |
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188 \begin{verbatim} |
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189 In []: a4 |
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190 \end{verbatim} |
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191 |
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192 All elements are type casted to string type |
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193 \end{frame} |
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194 \begin{frame} |
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195 \frametitle{\texttt{identity()}, \texttt{zeros()} methods} |
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196 \label{sec-12} |
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197 |
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198 \begin{itemize} |
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199 \item \texttt{identity(n)} |
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200 Creates an identity matrix, a square matrix of order (n, n) with diagonal elements 1 and others 0. |
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201 \item \texttt{zeros((m, n))} |
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202 Creates an \texttt{m X n} matrix with all elements 0. |
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203 \end{itemize} |
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204 \end{frame} |
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205 \begin{frame} |
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206 \frametitle{Learning exercise} |
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207 \label{sec-13} |
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208 |
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209 \begin{itemize} |
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210 \item Find out about |
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211 |
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212 \begin{itemize} |
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213 \item \texttt{zeros\_like()} |
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214 \item \texttt{ones()} |
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215 \item \texttt{ones\_like()} |
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216 \end{itemize} |
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217 |
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218 \end{itemize} |
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219 \end{frame} |
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220 \begin{frame} |
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221 \frametitle{Array operations} |
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222 \label{sec-14} |
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223 |
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224 \begin{itemize} |
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225 \item \texttt{a1 * 2} |
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226 returns a new array with all elements of \texttt{a1} multiplied by \texttt{2}. |
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227 |
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228 \begin{itemize} |
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229 \item Similarly \texttt{+}, \texttt{-} \& \texttt{/}. |
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230 \end{itemize} |
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231 |
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232 \item \texttt{a1 + 2} |
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233 returns a new array with all elements of \texttt{a1} summed with \texttt{2}. |
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234 \item \texttt{a1 += 2} |
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235 adds \texttt{2} to all elements of array \texttt{a1}. |
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236 |
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237 \begin{itemize} |
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238 \item Similarly \texttt{-=}, \texttt{*=} \& \texttt{/=}. |
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239 \end{itemize} |
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240 |
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241 \item \texttt{a1 + a2} |
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242 does elements-wise addition. |
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243 |
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244 \begin{itemize} |
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245 \item Similarly \texttt{-}, \texttt{*} \& \texttt{/}. |
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246 \end{itemize} |
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247 |
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248 \item \texttt{a1 * a2} |
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249 does element-wise multiplication |
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250 \end{itemize} |
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251 |
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252 |
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253 \textbf{Note} - array(A) * array(B) does element wise multiplication and not matrix multiplication |
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254 \end{frame} |
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255 \begin{frame} |
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256 \frametitle{Summary} |
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257 \label{sec-15} |
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258 |
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259 In this tutorial we covered, |
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260 \begin{itemize} |
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261 \item Basics of arrays |
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262 \item Creating arrays |
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263 \item Arrays from lists |
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264 \item Basic array operations |
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265 \end{itemize} |
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266 \end{frame} |
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267 \begin{frame} |
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268 \frametitle{Thank you!} |
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269 \label{sec-16} |
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270 |
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271 \begin{block}{} |
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272 \begin{center} |
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273 This spoken tutorial has been produced by the |
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274 \textcolor{blue}{FOSSEE} team, which is funded by the |
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275 \end{center} |
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276 \begin{center} |
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277 \textcolor{blue}{National Mission on Education through \\ |
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278 Information \& Communication Technology \\ |
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279 MHRD, Govt. of India}. |
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280 \end{center} |
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281 \end{block} |
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282 \end{frame} |
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283 |
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284 \end{document} |
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