# HG changeset patch # User Shantanu # Date 1271860756 -19800 # Node ID 47a2ba7beaf867b46887a240a660d60330cd5891 # Parent 0bc1c9ec4fcf1d56403b99f260e62e8d83bb093b Added strings presentation. diff -r 0bc1c9ec4fcf -r 47a2ba7beaf8 presentations/strings.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/presentations/strings.tex Wed Apr 21 20:09:16 2010 +0530 @@ -0,0 +1,112 @@ +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%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} +\usepackage[latin1]{inputenc} +%\usepackage{times} +\usepackage[T1]{fontenc} + +% Taken from Fernando's slides. +\usepackage{ae,aecompl} +\usepackage{mathpazo,courier,euler} +\usepackage[scaled=.95]{helvet} + +\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{Python for Scientific Computing : Strings and I/O operations} + +\author[FOSSEE] {FOSSEE} + +\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay} +\date{} + +% DOCUMENT STARTS +\begin{document} + +\begin{frame} + \maketitle +\end{frame} + +\begin{frame} + \frametitle{About the Session} + \begin{block}{Goal} + \begin{itemize} + \item Strings and their manipulations + \item I/O operations + \end{itemize} + \end{block} + \begin{block}{Prerequisites} + \begin{itemize} + \item Writing Python scripts + \item Basics of Lists + \end{itemize} + \end{block} +\end{frame} + +\begin{frame}[fragile] + \frametitle{Summary} + \begin{block}{} + \begin{itemize} + \item Creating string variables + \item Manipulating strings + \item I/O operations + \item Comments + \item Dynamically typed nature + \end{itemize} + \end{block} +\end{frame} + +\begin{frame} + \frametitle{Thank you!} + \begin{block}{} + This session is part of \textcolor{blue}{FOSSEE} project funded by: + \begin{center} + \textcolor{blue}{NME through ICT from MHRD, Govt. of India}. + \end{center} + \end{block} +\end{frame} + +\end{document} diff -r 0bc1c9ec4fcf -r 47a2ba7beaf8 strings.org --- a/strings.org Wed Apr 21 18:43:36 2010 +0530 +++ b/strings.org Wed Apr 21 20:09:16 2010 +0530 @@ -24,11 +24,13 @@ look at how to do elementary string manipulation, and simple input and output operations. - As, we have seen in previous tutorials, anything enclosed within - quotes is a string. For example - + In Python anything enclosed within quotes is a string. Lets get + started by starting ipython interpreter. We shall create some + string variables by: a = 'This is a string' print a + type(a) shows it is 'str' b = "This too!" print b @@ -44,11 +46,12 @@ These are special type of strings, called docstrings, which shall be discussed along with functions. - Like lists, which we already saw, string elements can be accessed - with their indexes. The indexing here, also, begins from 0. + Like lists and arrays, which we have already seen, string elements + can also be accessed with their indexes. The indexing here, also, + begins from 0. - print a[0] - print a[5] + print a[0] gives us 'T' + print a[5] gives us 'i' which is 6th character. To access the last element, we can use -1 as the index! print a[-1] @@ -60,7 +63,9 @@ len(a) Python's strings support the operations + and * + + concatenates two strings. a + b + and * is used for replicating a string for given number of times. a * 4 What do you think would happen when you do a * a? It's obviously an error since, it doesn't make any logical sense. @@ -93,20 +98,21 @@ Python also has a 'join' function, which does the opposite of what split does. ' '.join(alist) will return the original string a. + This function takes list of elements(in our case alist) to be joined. '-'.join(alist) will return a string with the spaces in the string 'a' replaced with hyphens. At times we want our output or message in a particular format with variables embedded, something like printf in C. For those situations python provides a provision. First lets create some - variables + variables say * formatting - printf style * In []: x, y = 1, 1.234 In []: print 'x is %s, y is %s' %(x, y) Out[]: 'x is 1, y is 1.234' Here %s means string, you can also try %d or %f for integer and - float values. + float values respectively. * formatting - printf style * @@ -151,11 +157,11 @@ Before we wind up, a couple of miscellaneous things. As you may have already noticed, Python is a dynamically typed language, that is you don't have to specify the type of a variable - when using a new one. You don't have to do anything special, to use + when using a new one. You don't have to do anything special, to 'reuse' a variable that was of int type as a float or string. - a = 1 - a = 1.1 + a = 1 here a is integer + a = 1.1 now a float a = "Now I am a string!" Comments in Python start with a pound or hash sign. Anything after @@ -166,7 +172,7 @@ a = "# not a comment" we come to the end of this tutorial on strings introduction of Data types in - Python. In this tutorial we have learnt what are supported data types, - supported operations and performing simple IO operations in Python. + Python. In this tutorial we have learnt what are supported operations and + performing simple IO operations in Python. *** Notes