[Tex/LaTex] Simple Characteristic Function or Step Function in pgfplots

Question

How would I go about creating a simple characteristic function plot such as this in pgfplots? It is not necessary for my Latex processor to generate the plot based on a function, manually drawing the coordinates and lines will suffice. Is pgfplots an appropriate tool for the job?

Answer 1

Here's a simple solution using the pgfplots package

% arara: pdflatex
% !arara: indent: {overwrite: yes}
\documentclass[tikz]{standalone}
\usepackage{pgfplots}

\pgfplotsset{every axis/.append style={
    axis x line=middle,    % put the x axis in the middle
    axis y line=middle,    % put the y axis in the middle
    axis line style={<->}, % arrows on the axis
    xlabel={$x$},          % default put x on x-axis
    ylabel={$y$},          % default put y on y-axis
    },
    cmhplot/.style={color=red,mark=none,line width=1pt,<->},
    soldot/.style={color=red,only marks,mark=*},
    holdot/.style={color=red,fill=white,only marks,mark=*},
}

\tikzset{>=stealth}
\begin{document}

\begin{tikzpicture}
    \begin{axis}[
            xmin=-3.5,xmax=5.5,
            ymin=-1,ymax=2,
        ]
        \addplot[cmhplot,<-,domain=-3:1]{0};
        \addplot[cmhplot,-,domain=1:4]{1};
        \addplot[cmhplot,->,domain=4:5]{0};
        \addplot[holdot]coordinates{(1,0)(4,1)};
        \addplot[soldot]coordinates{(1,1)(4,0)};
    \end{axis}
\end{tikzpicture}
\end{document}

For reference, here's a solution using pstricks

% arara: latex
% arara: dvips
% arara: ps2pdf
\documentclass[pstricks,border=2mm]{standalone}

\usepackage{pst-plot}
\psset{algebraic=true}          

\begin{document}
        \begin{pspicture}(-3.5,-1)(6,2)
            \psaxes[dx=2,Dx=2]{<->}(0,0)(-3.5,-1)(6,2)[$x$,-90][$y$,0]
            \psplot[linecolor=blue,arrows=<-o]{-3}{1}{0}
            \psplot[linecolor=blue,arrows=*-o]{1}{4}{1}
            \psplot[linecolor=blue,arrows=*->]{4}{5}{0}
        \end{pspicture}
\end{document}