\documentclass[12pt]{article}

\title{Interactive Plotting}

\author{FOSSEE}

\usepackage{listings}

\lstset{language=Python,

    basicstyle=\ttfamily,

commentstyle=\itshape\bfseries,

showstringspaces=false,

}

\newcommand{\typ}[1]{\lstinline{#1}}

\usepackage[english]{babel}

\usepackage[latin1]{inputenc}

\usepackage{times}

\usepackage[T1]{fontenc}

\usepackage{ae,aecompl}

\usepackage{mathpazo,courier,euler}

\usepackage[scaled=.95]{helvet}

\begin{document}

\date{}

\vspace{-1in}

\begin{center}

\LARGE{Interactive Plotting}\\

\large{FOSSEE}

\end{center}

\section{Starting up...}

\begin{lstlisting}

  $ ipython -pylab  

\end{lstlisting}

Exiting 

\begin{lstlisting}     

In [2]: (Ctrl-D)^D

Do you really want to exit ([y]/n)? y

\end{lstlisting} %$

\section{Plotting}

\subsection{linspace}

\typ{In []: x = linspace(start, stop, num)}\\

\typ{linspace} returns array of length \typ{num}, for which \typ{x[0] = start} and \typ{x[num-1] = stop} \\

\emph{Please note indices of array starts from zero(0)}

\subsection{plot}

\typ{In []: plot(X, Y)}\\

For given arrays of equal length(above case X and Y), \typ{plot} plots the corresponding *x* and *y* pairs taken from X and Y.

\subsection{Colors of plots}

\typ{In []: plot(y, sin(y), 'g')}\\

Plots graph with green color. Other options available are:

\begin{lstlisting}

  'r' ---> Red

  'b' ---> Blue

  'r' ---> Red 

  'c' ---> Cyan 

  'm' ---> Magenta

  'y' ---> Yellow

  'k' ---> Black 

  'w' ---> White

\end{lstlisting}

One can set the width of the plotline using optional argument \typ{linewidth}. For example:\\

\typ{In []: plot(x, cos(x), 'r', linewidth=2)}\\

Plots the line with linewidth = 2

\subsection{label and title}

\typ{In []: xlabel('Length') #sets *x* axis label to Length}\\ 

\typ{In []: ylabel('Time') #sets *y* axis label to Time.}\\

\typ{In []: title('Sinusoids') #sets title of plot}\\

\\

\textbf{Additionally}\\

Pylab accepts TeX equation expressions in any text expression. To get something like:\\

$\sigma_i=15$ \\

on title of figure use: 

\begin{lstlisting}

In []: title('$\sigma_i=15$')

\end{lstlisting}  

Same way one can have TeX expression on xlabel, ylabel etc.

\subsection{legends}

\typ{In []: legend('sin(x)',loc=center)} \\

Places a legend on the current plot at location *loc*.\\

Apart from \typ{center}, some other \typ{loc} which can be specified are:

\begin{lstlisting}

'best'

'right'

'upper right'

'upper left'      

'lower left'      

'lower right'     

'center left'     

'center right'    

'lower center'    

'upper center'    

\end{lstlisting}

\newpage

One can also mention explicit co-ordinates for placement of legend. 

\begin{lstlisting}

In []: legend(['sin(2y)'], loc=(.8,.1)) 

\end{lstlisting}

\typ{loc = 0, 1} (top left position of graph)\\

\typ{loc = 0.5, 0.5} (center of graph).

\subsection{Annotate}

\typ{In []: annotate('local max', xy=(1.5, 1))}\\

Annotates current plot with text, 'local max', at position specified to \typ{xy}.

\subsection{Saving figures}

\typ{In []: savefig('sinusoids.png')}\\

Saves the current figure with file name 'sinusoids.png' in current working directory. One can save figure in any of these formats: png, pdf, ps, eps and svg.

\subsection{Miscellaneous}

\typ{In []: clf() #Clears the current plot area}\\

\typ{In []: close() #Closes the figure}

\section{Saving and running scripts}

\begin{itemize}

  \item \typ{\%hist}\\

  It returns the logs of all commands(including mistakes) used in IPython interpreter.

  \item \typ{\%hist -n}\\

It disables the line number representation of logs.

  \item \typ{\%save four\_plot.py 16 18-27}\\

For creating a script named four\_plot which includes line 16 and line 18 to 27 of logs.

  \item \typ{\%run -i four\_plot.py}\\

Running the python script inside IPython interpreter.

\end{itemize}

\section{Example}

  \begin{lstlisting}

In []: x = linspace(0, 2*pi, 50)

In []: plot(x, sin(x), 'g')

In []: plot(x, cos(x), 'r', linewidth=2)

In []: xlabel('x')

In []: title('Sinusoidal Waves')

In []: legend(['sin(x)', 'cos(x)'])

In []: annotate('origin', xy=(0, 0))

In []: xmin, xman = xlim()  # returns current X axis limits.

In []: ymin, ymax = ylim()

In []: xlim(0, 2 * pi) # sets the X axis limits to passed values

In []: ylim(ymin - 0.2, ymax + 0.2) 

In []: savefig('sin.png')   # Save figure

In []: close()              

  \end{lstlisting}

\section{References}

\begin{itemize}

  \item For documentation on IPython refer: \\ http://ipython.scipy.org/moin/Documentation

  \item Plotting(matplotlib) related documentation are available at:\\ http://matplotlib.sourceforge.net/contents.html

  \item Explore examples and plots based on matplotlib at \\ http://matplotlib.sourceforge.net/examples/index.html

\end{itemize}

\end{document}