# HG changeset patch # User Puneeth Chaganti # Date 1289366241 -19800 # Node ID e62bc810999c568f5737fbd1624e4486af8640bf # Parent 975677bf1b8a4c765d1a41c7a5120f995c0e5f68 Cleaned up getting started with strings LO. diff -r 975677bf1b8a -r e62bc810999c getting-started-strings/quickref.tex --- a/getting-started-strings/quickref.tex Wed Nov 10 10:24:03 2010 +0530 +++ b/getting-started-strings/quickref.tex Wed Nov 10 10:47:21 2010 +0530 @@ -1,8 +1,8 @@ -Creating a linear array:\\ -{\ex \lstinline| x = linspace(0, 2*pi, 50)|} +Creating a string:\\ +{\ex \lstinline| s = ``Hello World''|} -- Single quotes and triple +quotes can also be used. -Plotting two variables:\\ -{\ex \lstinline| plot(x, sin(x))|} +Accessing individual elements:\\ +{\ex \lstinline| s[5]|} -- Elements can be accessed with their index -Plotting two lists of equal length x, y:\\ -{\ex \lstinline| plot(x, y)|} +Strings are immutable. diff -r 975677bf1b8a -r e62bc810999c getting-started-strings/script.rst --- a/getting-started-strings/script.rst Wed Nov 10 10:24:03 2010 +0530 +++ b/getting-started-strings/script.rst Wed Nov 10 10:47:21 2010 +0530 @@ -30,9 +30,9 @@ {{{ Show the slide containing the outline }}} -In this tutorial, we will learn what do we actually mean by strings in -python, how python supports the use of strings. We will also learn -some of the operations that can be performed on strings. +In this tutorial, we will look at what we really mean by strings, how +python supports the use of strings and some of the operations that can +be performed on strings. {{{ Shift to terminal and start ipython }}} @@ -42,10 +42,9 @@ on the terminal -So what are strings? In Python anything within either single quotes +So, what are strings? In Python anything within either single quotes or double quotes or triple single quotes or triple double quotes are -strings. This is true whatsoever, even if there is only one character -within the quotes +strings. {{{ Type in ipython the following and read them as you type }}}:: @@ -54,19 +53,21 @@ '''This is a string as well''' """This is also a string""" 'p' + "" -Having more than one control character to define strings come as very -handy when one of the control characters itself is part of the -string. For example:: +Note that it really doesn't matter how many characters are present in +the string. The last example is a null string or an empty string. + +Having more than one control character to define strings is handy when +one of the control characters itself is part of the string. For +example:: "Python's string manipulation functions are very useful" -In this case we use single quote for apostrophe. If we had only single -quote to define strings we should have a clumsy way of escaping the -single quote character to make it part of the string. Hence this is a -very handy feature. +By having multiple control characters, we avoid the need for +escaping characters -- in this case the apostrophe. -The triple quoted strings let us define multi-lines strings without +The triple quoted strings let us define multi-line strings without using any escaping. Everything within the triple quotes is a single string no matter how many lines it extends:: @@ -99,19 +100,63 @@ gives another string in which the original string 'Hello' is repeated 5 times. -Since strings are collections we can access individual items in the -string using the subscripts:: +Following is an exercise that you must do. + +%% %% Obtain the string ``%% -------------------- %%`` (20 hyphens) + without typing out all the twenty hyphens. + +Please, pause the video here. Do the exercise and then continue. + +:: + + s = "%% " + "-"*20 + " %%" + +Let's now look at accessing individual elements of strings. Since, +strings are collections we can access individual items in the string +using the subscripts:: a[0] gives us the first character in the string. The indexing starts from 0 -for the first character up to n-1 for the last character. We can -access the strings from the end using negative indices:: +for the first character and goes up to n-1 for the last character. We +can access the strings from the end using negative indices:: + + a[-1] - a[-2] +gives us the last element of the string and +:: + + a[-2] gives us second element from the end of the string +Following is an exercise that you must do. + +%% %% Given a string, ``s = "Hello World"``, what is the output of:: + + s[-5] + s[-10] + s[-15] + +Please, pause the video here. Do the exercise and then continue. + +:: + + s[-5] + +gives us 'W' +:: + + s[-10] + +gives us 'e' and +:: + + s[-15] + +gives us an ``IndexError``, as should be expected, since the string +given to us is only 11 characters long. + Let us attempt to change one of the characters in a string:: a = 'hello' @@ -132,7 +177,7 @@ * How to define strings * Different ways of defining a string - * String concatenation and repeatition + * String concatenation and repetition * Accessing individual elements of the string * Immutability of strings diff -r 975677bf1b8a -r e62bc810999c getting-started-strings/slides.org --- a/getting-started-strings/slides.org Wed Nov 10 10:24:03 2010 +0530 +++ b/getting-started-strings/slides.org Wed Nov 10 10:47:21 2010 +0530 @@ -18,7 +18,7 @@ #+LaTeX_HEADER: commentstyle=\color{red}\itshape, stringstyle=\color{darkgreen}, #+LaTeX_HEADER: showstringspaces=false, keywordstyle=\color{blue}\bfseries} -#+TITLE: Accessing parts of arrays +#+TITLE: #+AUTHOR: FOSSEE #+EMAIL: #+DATE: @@ -30,81 +30,38 @@ #+OPTIONS: TeX:t LaTeX:nil skip:nil d:nil todo:nil pri:nil tags:not-in-toc * Outline - - Manipulating one and multi dimensional arrays - - Access and change individual elements - - Access and change rows and columns - - Slicing and striding on arrays to access chunks - - Read images into arrays and manipulations -* Sample Arrays - #+begin_src python - In []: A = array([12, 23, 34, 45, 56]) - - In []: C = array([[11, 12, 13, 14, 15], - [21, 22, 23, 24, 25], - [31, 32, 33, 34, 35], - [41, 42, 43, 44, 45], - [51, 52, 53, 54, 55]]) - - #+end_src +*** Defining strings +*** Concatenation +*** Accessing individual elements +*** Immutability of strings * Question 1 - Change the last column of ~C~ to zeroes. + Obtain the string ~%% -------------------- %%~ (20 hyphens) without + typing out all the twenty hyphens. * Solution 1 #+begin_src python - In []: C[:, -1] = 0 + s = "%% " + "-"*20 + " %%" #+end_src * Question 2 - Change ~A~ to ~[11, 12, 13, 14, 15]~. + Given a string, ~s~ which is ~Hello World~ , what is the output of:: + #+begin_src python + s[-5] + s[-10] + s[-15] + #+end_src * Solution 2 #+begin_src python - In []: A[:] = [11, 12, 13, 14, 15] - #+end_src -* squares.png - #+begin_latex - \begin{center} - \includegraphics[scale=0.6]{squares} - \end{center} - #+end_latex -* Question 3 - - obtain ~[22, 23]~ from ~C~. - - obtain ~[11, 21, 31, 41]~ from ~C~. - - obtain ~[21, 31, 41, 0]~. -* Solution 3 - #+begin_src python - In []: C[1, 1:3] - In []: C[0:4, 0] - In []: C[1:5, 0] - #+end_src -* Question 4 - Obtain ~[[23, 24], [33, -34]]~ from ~C~ -* Solution 4 - #+begin_src python - In []: C[1:3, 2:4] - #+end_src -* Question 5 - Obtain the square in the center of the image -* Solution 5 - #+begin_src python - In []: imshow(I[75:225, 75:225]) - #+end_src -* Question 6 - Obtain the following - #+begin_src python - [[12, 0], [42, 0]] - [[12, 13, 14], [0, 0, 0]] - #+end_src - -* Solution 6 - #+begin_src python - In []: C[::3, 1::3] - In []: C[::4, 1:4] + 'W' + 'e' + IndexError #+end_src * Summary - You should now be able to -- - - Manipulate 1D \& Multi dimensional arrays - - Access and change individual elements - - Access and change rows and columns - - Slice and stride on arrays - - Read images into arrays and manipulate them. + In this tutorial we have learnt + + How to define strings + + Different ways of defining a string + + String concatenation and repetition + + Accessing individual elements of the string + + Immutability of strings + * Thank you! #+begin_latex \begin{block}{} diff -r 975677bf1b8a -r e62bc810999c getting-started-strings/slides.tex --- a/getting-started-strings/slides.tex Wed Nov 10 10:24:03 2010 +0530 +++ b/getting-started-strings/slides.tex Wed Nov 10 10:47:21 2010 +0530 @@ -1,95 +1,118 @@ -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -%Tutorial slides on Python. -% -% Author: FOSSEE -% Copyright (c) 2009, FOSSEE, IIT Bombay -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% - -\documentclass[14pt,compress]{beamer} -%\documentclass[draft]{beamer} -%\documentclass[compress,handout]{beamer} -%\usepackage{pgfpages} -%\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm] - -% Modified from: generic-ornate-15min-45min.de.tex -\mode -{ - \usetheme{Warsaw} - \useoutertheme{infolines} - \setbeamercovered{transparent} -} - -\usepackage[english]{babel} +% Created 2010-11-10 Wed 10:46 +\documentclass[presentation]{beamer} \usepackage[latin1]{inputenc} -%\usepackage{times} \usepackage[T1]{fontenc} - -\usepackage{ae,aecompl} -\usepackage{mathpazo,courier,euler} -\usepackage[scaled=.95]{helvet} +\usepackage{fixltx2e} +\usepackage{graphicx} +\usepackage{longtable} +\usepackage{float} +\usepackage{wrapfig} +\usepackage{soul} +\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}} -\definecolor{darkgreen}{rgb}{0,0.5,0} - -\usepackage{listings} -\lstset{language=Python, - basicstyle=\ttfamily\bfseries, - commentstyle=\color{red}\itshape, - stringstyle=\color{darkgreen}, - showstringspaces=false, - keywordstyle=\color{blue}\bfseries} - -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -% Macros -\setbeamercolor{emphbar}{bg=blue!20, fg=black} -\newcommand{\emphbar}[1] -{\begin{beamercolorbox}[rounded=true]{emphbar} - {#1} - \end{beamercolorbox} -} -\newcounter{time} -\setcounter{time}{0} -\newcommand{\inctime}[1]{\addtocounter{time}{#1}{\tiny \thetime\ m}} - -\newcommand{\typ}[1]{\lstinline{#1}} - -\newcommand{\kwrd}[1]{ \texttt{\textbf{\color{blue}{#1}}} } - -% Title page -\title{Your Title Here} - -\author[FOSSEE] {FOSSEE} - -\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay} +\title{} +\author{FOSSEE} \date{} -% DOCUMENT STARTS +\usetheme{Warsaw}\usecolortheme{default}\useoutertheme{infolines}\setbeamercovered{transparent} \begin{document} + + + + + + + + + + \begin{frame} - \maketitle +\frametitle{Outline} +\label{sec-1} +\begin{itemize} + +\item Defining strings\\ +\label{sec-1_1}% +\item Concatenation\\ +\label{sec-1_2}% +\item Accessing individual elements\\ +\label{sec-1_3}% +\item Immutability of strings\\ +\label{sec-1_4}% +\end{itemize} % ends low level \end{frame} +\begin{frame} +\frametitle{Question 1} +\label{sec-2} + Obtain the string \texttt{\%\% -------------------- \%\%} (20 hyphens) without + typing out all the twenty hyphens. +\end{frame} \begin{frame}[fragile] - \frametitle{Outline} - \begin{itemize} - \item - \end{itemize} +\frametitle{Solution 1} +\label{sec-3} + +\lstset{language=Python} +\begin{lstlisting} +s = "%% " + "-"*20 + " %%" +\end{lstlisting} \end{frame} +\begin{frame}[fragile] +\frametitle{Question 2} +\label{sec-4} -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% -%% All other slides here. %% -%% The same slides will be used in a classroom setting. %% -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% - + Given a string, \texttt{s} which is \texttt{Hello World} , what is the output of:: +\lstset{language=Python} +\begin{lstlisting} +s[-5] +s[-10] +s[-15] +\end{lstlisting} +\end{frame} \begin{frame}[fragile] - \frametitle{Summary} - \begin{itemize} - \item - \end{itemize} +\frametitle{Solution 2} +\label{sec-5} + +\lstset{language=Python} +\begin{lstlisting} +'W' +'e' +IndexError +\end{lstlisting} \end{frame} - \begin{frame} - \frametitle{Thank you!} +\frametitle{Summary} +\label{sec-6} + + In this tutorial we have learnt +\begin{itemize} +\item How to define strings +\item Different ways of defining a string +\item String concatenation and repetition +\item Accessing individual elements of the string +\item Immutability of strings +\end{itemize} + + +\end{frame} +\begin{frame} +\frametitle{Thank you!} +\label{sec-7} + \begin{block}{} \begin{center} This spoken tutorial has been produced by the diff -r 975677bf1b8a -r e62bc810999c progress.org --- a/progress.org Wed Nov 10 10:24:03 2010 +0530 +++ b/progress.org Wed Nov 10 10:47:21 2010 +0530 @@ -15,7 +15,7 @@ |---------+----------------------------------------+-------+----------+-----------------+-----------| | 3.1 LO: | getting started with lists | 2 | Amit | Anoop(Done) | | | 3.2 LO: | getting started with =for= | 2 | Anoop | Nishanth (Done) | | -| 3.3 LO: | getting started with strings | 2 | Madhu | Punch (Pending) | | +| 3.3 LO: | getting started with strings | 2 | Madhu | Punch (Done) | | | 3.4 LO: | getting started with files | 3 | Punch | Anoop(Done) | | | 3.5 LO: | parsing data | 3 | Nishanth | Amit (Done) | | | 3.6 LO: | statistics | 2 | Amit | Punch (Done) | |