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%Tutorial slides on Python.

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% Author: FOSSEE 

% Copyright (c) 2009, FOSSEE, IIT Bombay

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% Title page

\title[Basic Python]{Python language: Basics}

\author[FOSSEE Team] {The FOSSEE Group}

\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}

\date[] {1 May, 2010\\Day 2, Session 1}

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%% Delete this, if you do not want the table of contents to pop up at

%% the beginning of each subsection:

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  \begin{frame}<beamer>

    \frametitle{Outline}

    \tableofcontents[currentsection,currentsubsection]

  \end{frame}

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    \frametitle{Outline}

    \tableofcontents[currentsection,currentsubsection]

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% DOCUMENT STARTS

\begin{document}

\begin{frame}

  \titlepage

\end{frame}

\begin{frame}

  \frametitle{Outline}

  \tableofcontents

  % You might wish to add the option [pausesections]

\end{frame}

\section{Data types}

\begin{frame}

  \frametitle{Primitive Data types}

  \begin{itemize}

    \item Numbers: float, int, complex

    \item Strings

    \item Booleans

  \end{itemize}

\end{frame}

\subsection{Numbers}

\begin{frame}[fragile]

  \frametitle{Numbers}

  \begin{itemize}

    \item \kwrd{int}\\ whole number, no matter what the size!

  \begin{lstlisting}

In []: a = 13

In []: b = 99999999999999999999

  \end{lstlisting}

    \item \kwrd{float}

  \begin{lstlisting}

In []: p = 3.141592

  \end{lstlisting}

  \end{itemize}

\end{frame}

\begin{frame}[fragile]

\frametitle{Complex numbers}

  \begin{lstlisting}

In []: c = 3+4j

In []: abs(c)

Out[]: 5.0

In []: c.imag

Out[]: 4.0

In []: c.real

Out[]: 3.0

  \end{lstlisting}

\end{frame}

\subsection{Booleans}

\begin{frame}[fragile]

  \frametitle{Booleans}

  \begin{lstlisting}

In []: t = True

In []: F = not t

In []: F or t

Out[]: True

In []: F and t

Out[]: False

  \end{lstlisting}

  \inctime{5}

\end{frame}

\begin{frame}[fragile]

  \frametitle{( )  for precedence}

  \begin{lstlisting}

In []: a = False

In []: b = True

In []: c = True

In []: (a and b) or c

Out[]: True

In []: a and (b or c)

Out[]: False

  \end{lstlisting}

  \inctime{5}

\end{frame}

\subsection{Strings}

\begin{frame}[fragile]

  \frametitle{Strings}

Strings were introduced previously, let us now look at them in a little more detail.

  \begin{lstlisting}

In []: w = "hello"

In []: print w[0] + w[2] + w[-1]

Out[]: hlo

In []: len(w)

Out[]: 5

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Strings \ldots}

  \emphbar{Strings are immutable}

  \begin{lstlisting}

In []: w[0] = 'H' 

  \end{lstlisting}

  \pause

  \begin{lstlisting}

--------------------------------------------

TypeError  Traceback (most recent call last)

<ipython console> in <module>()

TypeError: 'str' object does not

         support item assignment

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{String methods}

  \begin{lstlisting}

In []: a = 'Hello World'

In []: a.startswith('Hell')

Out[]: True

In []: a.endswith('ld')

Out[]: True

In []: a.upper()

Out[]: 'HELLO WORLD'

In []: a.lower()

Out[]: 'hello world'

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{A bit about IPython}

  Recall, we showed a few features of IPython, here is one more:

  \begin{itemize}

    \item IPython provides better help

    \item object.function?

    \begin{lstlisting}

In []: a = 'Hello World'

In []: a.lower?

    \end{lstlisting}

  \end{itemize}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Still with strings}

  \begin{itemize}

    \item We saw split() yesterday

    \item join() is the opposite of split()

  \end{itemize}

  \begin{lstlisting}

In []: ''.join(['a', 'b', 'c'])

Out[]: 'abc'

In []: ', '.join(['a', 'b', 'c'])

Out[]: 'a, b, c'

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

\frametitle{String formatting}

  \begin{lstlisting}

In []: x, y = 1, 1.234

In []: 'x is %s, y is %s' %(x, y)

Out[]: 'x is 1, y is 1.234'

  \end{lstlisting}

  \begin{itemize}

    \item \emph{\%d}, \emph{\%f} etc. available

  \end{itemize}

  \emphbar{\url{http://docs.python.org/library/stdtypes.html}}

  \inctime{10}

\end{frame}

\section{Operators}

\begin{frame}[fragile]

  \frametitle{Arithmetic operators}

  \small

  \begin{lstlisting}

In []: 1786 % 12

Out[]: 10

In []: 45 % 2

Out[]: 1

In []: 864675 % 10

Out[]: 5

In []: 3124 * 126789

Out[]: 396088836

In []: big = 1234567891234567890 ** 3

In []: verybig = big * big * big * big

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Arithmetic operators}

  \begin{lstlisting}

In []: 17 / 2

Out[]: 8

In []: 17 / 2.0

Out[]: 8.5

In []: 17.0 / 2

Out[]: 8.5

In []: 17.0 / 8.5

Out[]: 2.0

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Arithmetic operators}

  \begin{lstlisting}

In []: a = 7546

In []: a += 1

In []: a

Out[]: 7547

In []: a -= 5

In []: a

In []: a *= 2

In []: a /= 5

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{String operations}

  \begin{lstlisting}

In []: s = 'Hello'

In []: p = 'World'

In []: s + p 

Out[]: 'HelloWorld'

In []: s * 4

Out[]: 'HelloHelloHelloHello'

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{String operations \ldots}

  \begin{lstlisting}

In []: s * s

  \end{lstlisting}

  \pause

  \begin{lstlisting}

--------------------------------------------

TypeError  Traceback (most recent call last)

<ipython console> in <module>()

TypeError: can`t multiply sequence by

                non-int of type `str`

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Relational and logical operators}

  \begin{lstlisting}

In []: p, z, n = 1, 0, -1

In []: p == n

Out[]: False

In []: p >= n

Out[]: True

In []: n < z < p

Out[]: True

In []: p + n != z

Out[]: False

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Built-ins}

  \begin{lstlisting}

In []: int(17 / 2.0)

Out[]: 8

In []: float(17 / 2)

Out[]: 8.0

In []: str(17 / 2.0)

Out[]: '8.5'

In []: round( 7.5 )

Out[]: 8.0

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Odds and ends}

  \begin{itemize}

    \item Case sensitive

    \item Dynamically typed $\Rightarrow$ need not specify a type

      \begin{lstlisting}

In []: a = 1

In []: a = 1.1

In []: a = "Now I am a string!"

      \end{lstlisting}

    \item Comments:

      \begin{lstlisting}

In []: a = 1  # In-line comments

In []: # A comment line.

In []: a = "# Not a comment!"

      \end{lstlisting}

  \end{itemize}

  \inctime{15}

\end{frame}

\section{Simple IO}

\begin{frame}[fragile]

  \frametitle{Simple IO: Console Input}

  \small

  \begin{itemize}

    \item raw\_input() waits for user input.

      \begin{lstlisting}

In []: a = raw_input()

5

In []: a

Out[]: '5'

In []: a = raw_input('Enter a value: ')

Enter a value: 5

      \end{lstlisting}

    \item Prompt string is optional.

    \item All keystrokes are Strings!

    \item \texttt{int()} converts string to int.

  \end{itemize}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Simple IO: Console output}

  \begin{itemize}

    \item \typ{print} is straight forward

    \item Put the following code snippet in a file \typ{hello1.py}

  \end{itemize}

  \begin{lstlisting}

print "Hello"

print "World"

In []: %run -i hello1.py

Hello

World

  \end{lstlisting}

\end{frame}

\begin{frame}[fragile]

  \frametitle{Simple IO: Console output \ldots}

Put the following code snippet in a file \typ{hello2.py}

  \begin{lstlisting}

print "Hello",

print "World"

In []: %run -i hello2.py

Hello World

  \end{lstlisting}

\emphbar{Note the distinction between \typ{print x} and \typ{print x,}}

\end{frame}