Renamed all LOs to match with their names in progress.org.

4 files changed, 776 insertions, 0 deletions

diff --git a/getting_started_with_arrays/quickref.tex b/getting_started_with_arrays/quickref.tex
new file mode 100644
index 0000000..10714c4
--- /dev/null
+++ b/getting_started_with_arrays/quickref.tex
@@ -0,0 +1,14 @@
+Creating an array:\\
+{\ex \lstinline|    a = array([[1,2,3,4],[5,6,7,8]])|}
+
+Finding shape of array:\\
+{\ex \lstinline|    a.shape|}
+
+Reshape an array:\\
+{\ex \lstinline|    a.reshape(4,2)|}
+
+Creating identity matrix:\\
+{\ex \lstinline|    identity(3)|}
+
+Creating matrix with all zeros:\\
+{\ex \lstinline|    z = zeros((4,2))|}
diff --git a/getting_started_with_arrays/script.rst b/getting_started_with_arrays/script.rst
new file mode 100644
index 0000000..65a9f93
--- /dev/null
+++ b/getting_started_with_arrays/script.rst
@@ -0,0 +1,343 @@
+.. Objectives
+.. ----------
+
+.. At the end of this tutorial, you will be able to 
+
+.. 1. Create arrays using data
+.. #. Create arrays from lists
+.. #. Basic array operations
+.. #. Creating identity matrix using ``identity()`` function.
+.. #. Learn about ``zeros()``, ``zeros_like()``, ``ones()``,
+      ``ones_like()`` functions.
+
+.. Prerequisites
+.. -------------
+
+..   1. should have ``ipython`` and ``pylab`` installed. 
+..   #. getting started with ``ipython``.
+..   #. getting started with lists.
+     
+..  Author: Anoop Jacob Thomas <anoop@fossee.in>
+    Internal Reviewer   : Puneeth 
+    External Reviewer   :
+    Language Reviewer   : Bhanukiran
+    Checklist OK?       : <11-11-2010,Anand, OK > [2010-10-05]
+
+===========================
+Getting started with Arrays
+===========================
+
+.. #[Puneeth: Prerequisites and Objectives are missing. Fill them in]
+
+{{{ show the welcome slide }}}
+
+Welcome to the spoken tutorial on getting started with arrays.
+
+{{{ switch to next slide, outline slide }}}
+
+In this tutorial, we will learn about the data structure called an array, how to convert
+a list into an array, operations on arrays and also why an array is preferred
+to lists.
+
+.. #[Puneeth: Fix the grammar above.]
+
+{{{ switch to next slide on overview of array }}}
+
+Arrays are homogeneous data structures. Unlike lists, arrays cannot have
+heterogeneous data elements, that is, they can have only one type of data 
+as their entries, be them all integers, strings, or maybe floats, but not a mix.
+
+.. #[Puneeth: Use multiple short sentences, rather than one long sentence
+   I would've written something like this. 
+
+   Unlike lists, arrays are homogeneous data structures. They can have only
+   type of data, ....]
+
+Arrays of a given length are comparatively much faster in mathematical
+operations than lists of the same length, because of the fact that they are
+homogeneous data structures.
+
+.. #[Puneeth: For what size of an array is that the comparison?
+
+{{{ switch to the next slide, creating arrays }}}
+
+Now let us see how to create arrays.
+
+Run your IPython interpreter with ``-pylab`` option, to load the required
+modules to work with arrays.
+{{{ take terminal and run the following command }}}
+::
+
+        ipython -pylab
+
+.. #[Puneeth: 'I am assuming' doesn't sound right. Ask them to open if it
+.. is not open?]
+
+To create an array we will use the function ``array()`` as,
+
+::
+
+    a1 = array([1,2,3,4])
+
+Notice that we created a one dimensional array here. Also notice the object
+we passed to create an array. We passed a list to create an array. 
+
+Now let us see how to create a two dimensional array. Pause here and try to
+do it yourself before looking at the solution.
+
+{{{ switch to next slide, creating two dimensional arrays }}}
+
+.. #[Puneeth: I don't think this question can be solved by an average
+.. viewer. Questions during the tutorial, should generally be to re-iterate
+.. concepts learnt? ]
+
+.. #[Puneeth: Also, you didn't even point out that we are converting a
+.. list, using the ``array`` function. Bring the later section about
+.. converting a list, here. A separate section is not necessary, IMHO.]
+
+We create two dimensional array by converting a list of lists to an array
+as,
+
+::
+
+    a2 = array([[1,2,3,4],[5,6,7,8]])
+
+.. #[Puneeth: Again, you could explain a bit about the fact that we are
+.. converting a list of lists.]
+
+Now let us use ``arange()`` function to create the same array as before.
+
+::
+
+    ar = arange(1,9)
+
+.. #[Puneeth: say, creating the same array as before. for some time I got
+.. confused .]
+
+And we obtained a one dimensional array with elements from 1 to 8.
+
+::
+
+    print ar
+
+.. #[Puneeth: be consistent with voice. say, we obtained... or something.]
+
+And how can we make it a two dimensional array of order 2 by 4? Pause 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,
+
+::
+
+    ar.reshape(2,4)
+    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 ``l1``
+
+::
+
+    l1 = [1,2,3,4]
+
+Now we can convert the list to an array as, 
+
+::
+
+    a3 = array(l1)
+
+
+{{{ switch to the next slide, problem statement of unsolved exercise 1 }}}
+
+Create a three dimensional array of the shape (2,2,4).
+
+.. #[Puneeth: s/order/shape or size ?]
+
+{{{ switch to the next slide, shape of an array }}}
+
+To find the shape of an array we can use the method ``.shape``, let us
+check the shape of the arrays we have created so far,
+
+.. #[Puneeth: s/object/method ?]
+
+::
+
+    a2.shape
+
+``a2.shape`` object is a tuple, and it returned a tuple (2, 4).
+
+.. #[Puneeth: first show a 2D array, so that it becomes easier to explain.
+.. Also, the word ``tuple`` need not be mentioned. ]
+
+{{{ switch to the next slide, unsolved exercise 2 }}}
+
+Find out the shape of the other arrays that we have created.
+
+.. #[Puneeth: solution missing.]
+
+It can be done as,
+::
+
+    a1.shape
+    a3.shape
+    ar.shape
+
+{{{ Array can have only a single type of data }}}
+
+.. #[Puneeth: I guess, this whole section can be skipped. If you want to
+.. keep this, just briefly mention that arrays are homogeneous in the
+.. intro, don't explain it there.]
+
+Now let us try to create a new array with a mix of elements and see what
+will happen,
+
+::
+
+    a4 = array([1,2,3,'a string'])
+
+Well, we would expect an error as it has been previously mentioned that arrays handle
+elements with the same datatype, but it didn't raise an error. Let us check the values
+in the new array created. In your IPython terminal type, 
+::
+
+    a4
+
+Did you notice it,
+
+{{{ switch to next slide, implicit type casting }}}
+
+.. #[Puneeth: typecasting may be unnecessary. (Also too advanced?) an
+.. average guy wouldn't use arrays with strings.]
+
+.. #[Puneeth: You may want to mention that float is the default dtype.]
+
+{{{ highlight all the array elements one by one using mouse movements }}}
+
+all the elements have been implicitly type casted as strings, though our
+first three elements were meant to be integers.
+
+.. #[Puneeth: when I type a4 it says some ``dtype`` etc. I don't understand
+.. what it is, can you explain? ;)]
+
+{{{ switch to the next slide, identity & zeros methods }}}
+
+.. #[Puneeth: something needs to motivate this. why are we suddenly talking
+.. of an identity matrix?]
+
+Now let us see how to create an identity matrix of a given size, that is a
+two-dimensional array  in  which all the diagonal elements are ones and rest of the
+elements are zeros. We can create an identity matrix using the function
+``identity()``.
+
+The function ``identity()`` takes an integer argument which specifies the
+size of the desired matrix,
+
+::
+
+    identity(3)
+
+As you can see the identity function returned a three by three square matrix
+with all the diagonal elements as ones and the rest of the elements as zeros.
+
+.. #[Puneeth: You say array here, matrix there -- it's a bit messed up.
+.. Clarify, explicitly.]
+
+``zeros()`` function accepts a tuple, which is the order of the array that we
+want to create, and it generates an array with all elements as zeros.
+
+{{{ switch to the next slide, problem statement of solved exercise 1 }}}
+
+Let us creates an array of the order four by five with all the elements
+zero. We can do it using the method zeros, ::
+
+    zeros((4,5))
+
+Notice that we passed a tuple to the function zeros.
+
+{{{ switch to next slide, learning exercise }}}
+
+We learned two functions ``identity()`` and ``zeros()``, find out more
+about the functions ``zeros_like()``, ``ones()``, ``ones_like()``.
+
+{{{ switch to next slide, array operations }}}
+
+Try the following, first check the value of a1,
+::
+
+    a1
+
+``a1`` is a single dimensional array, and now try,
+::
+
+    a1 * 2
+
+It returned a new array with all the elements multiplied by 2.
+::
+
+    a1
+
+note that the value of a1 still remains the same.
+
+Similarly with addition,
+::
+
+    a1 + 2
+
+it returns a new array, with all the elements summed with two. But
+again notice that the value of a1 has not been changed.
+::
+
+    a1
+
+You may change the value of a1 by simply assigning the newly returned
+array as,
+::
+
+    a1 += 2
+
+Notice the change in elements of a,
+::
+
+    a
+
+We can use all the mathematical operations with arrays, Now let us try this
+::
+
+   a1 = array([1,2,3,4])
+   a2 = array([1,2,3,4])
+   a1 + a2
+
+Returns an array with element by element addition,
+::
+
+    a1 * a2
+
+Returns an array with element by element multiplication, notice that it
+does not perform matrix multiplication.
+
+{{{ switch to next slide, summary slide }}}
+
+So this brings us to the end of this tutorial, in this tutorial we covered
+basics of arrays, learned how to create an array, saw how to convert a list
+to an array, and basic array operations etc.
+
+.. #[Puneeth: s/how to create an array/creating an array]
+
+{{{ switch to next slide, thank you }}}
+
+Thank you!
+
+.. 
+   Local Variables:
+   mode: rst
+   indent-tabs-mode: nil
+   sentence-end-double-space: nil
+   fill-column: 75
+   End:
diff --git a/getting_started_with_arrays/slides.org b/getting_started_with_arrays/slides.org
new file mode 100644
index 0000000..a5b315f
--- /dev/null
+++ b/getting_started_with_arrays/slides.org
@@ -0,0 +1,135 @@
+#+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
+
+
diff --git a/getting_started_with_arrays/slides.tex b/getting_started_with_arrays/slides.tex
new file mode 100644
index 0000000..7273c59
--- /dev/null
+++ b/getting_started_with_arrays/slides.tex
@@ -0,0 +1,284 @@
+% Created 2010-11-07 Sun 15:18
+\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}
+
+  \texttt{[1, 2, 3, 4]} is a list.
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{Creating two-dimensional array}
+\label{sec-4}
+
+\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}
+
+  here we convert a list of lists to an array making a 2-d array.
+\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-5}
+
+\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-6}
+
+\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-7}
+
+  Create a 3-dimensional array of the order (2, 2, 4).
+\end{frame}
+\begin{frame}[fragile]
+\frametitle{\texttt{.shape} of array}
+\label{sec-8}
+
+\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-9}
+
+  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-10}
+
+\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-11}
+
+\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-12}
+
+\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-13}
+
+\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-14}
+
+\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-15}
+
+  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-16}
+
+  \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}