Lollipop Plots Using PSTricks

[Denis Girou]

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The following message is a courtesy copy of an article
that has been posted to comp.text.tex as well.

>>>>> "Monson.Hayes" == mhh3  <mhh3 at eedsp.gatech.edu> writes:

    Monson.Hayes> I would like to generate a "lollipop" plot as one often does in plotting
    Monson.Hayes> discrete-time signals.  These look like,


    Monson.Hayes>     OOO      O
    Monson.Hayes>  O |   |   |  O  |
    Monson.Hayes>   |   |   |   |   |   |
    Monson.Hayes> --------

    Monson.Hayes> What I would like to do is read in an array of numbers using  \dataplot,

    Monson.Hayes> and have it generate a plot like this.  Although \dataplot would
    Monson.Hayes> generate
    Monson.Hayes> the "circles" at the appropriate points, it does not generate the
    Monson.Hayes> vertical
    Monson.Hayes> lines connecting them to the x-axis.  I am wondering if anyone has
    Monson.Hayes> modified
    Monson.Hayes> pst-plot.tex to do this, or can tell me how to make the modifications.
    Monson.Hayes> I do not know the postscript language.  Thanks.

  To obtain plots like:

                      OOO   O
                   O  |||   |   O
                   |  |||   |   |
                  ---------------
                         |
                         O

you must effectively define some internal TeX and PostScript macros,
as such result is not provided by existing functionalities. Here is
one way to do that:

\documentclass[a4paper]{article}

\usepackage{pst-plot}

\makeatletter

% D.G. addition begin - Jan.  6, 2000

\let\beginplot at LineToXAxis\beginplot at line
\def\endplot at LineToXAxis{\psLineToXAxis at ii}
\let\beginqp at LineToXAxis\beginqp at line
\let\doqp at LineToXAxis\doqp at line
\let\endqp at LineToXAxis\endqp at line
\let\testqp at LineToXAxis\testqp at line

% Adapted from \psline at ii
\def\psLineToXAxis at ii{%
% D.G. modification begin - Jan.  6, 2000
%\addto at pscode{\pst at cp \psline at iii \tx at Line}%
\addto at pscode{\pst at cp \psline at iii \tx at LineToXAxis}%
% D.G. modification end
\end at OpenObj}

\def\tx at LineToXAxis{LineToXAxis }

% Adapted from Line
\pst at def{LineToXAxis}<{%
NArray
n 0 eq not
  { n 1 eq { 0 0 /n 2 def } if
    ArrowA
    /n n 2 sub def
% D.G. modification begin - Jan.  6, 2000
%    n { Lineto } repeat
    CP 2 copy moveto pop 0 Lineto
    n { 2 copy moveto pop 0 Lineto } repeat
% D.G. modification end
    CP
    4 2 roll
    ArrowB
% D.G. modification begin - Jan.  6, 2000
    2 copy moveto pop 0
% D.G. modification end
    L
    pop pop } if}>

% D.G. addition end

\makeatother

\pagestyle{empty}

\begin{document}

\savedata{\Data}[{{(1,2),(3,3),(4,-1),(5,3),(7,3),(8,-2)}}]

\begin{pspicture}(0,-3)(9,4)
  \dataplot[plotstyle=LineToXAxis,linestyle=dotted,
            showpoints=true,dotstyle=o,dotsize=0.4]{\Data}
  \psaxes{<->}(0,0)(0,-3)(9,4)
\end{pspicture}

\end{document}


Denis Girou
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