[pstricks] \listplot, single point and regression

[Herbert Voss]

Poul Riis wrote:
> 1) Is it possible to read the coordinates of point no. n when using
> \listplot?

The nodes are named as N1 N2 N3 ...
This version needs the number of lines in the data file.
If your data is not comma separated then change the line

         \pnode(\Data){\NodeName}

to

         \pnode(! \Data ){\NodeName}

if space separated.



% the contents of the external data file "node.data"
\iffalse
   142.264,    0.0
   134.555,   46.193
   112.266,   87.3802
   77.8109,  119.098
   34.9237,  137.91
  -11.7481,  141.778
  -57.1467,  130.281
  -96.3526,  104.667
-125.117,    67.71
-140.323,    23.4158
-140.323,   -23.4159
-125.117,   -67.7101
  -96.3525, -104.667
  -57.1466, -130.281
  -11.748,  -141.778
   34.9237, -137.91
   77.8109, -119.098
  112.266,   -87.3802
  134.555,   -46.193
  142.264,     0.0
\fi

\documentclass[a4paper]{article}

\usepackage{pstricks,pst-plot,pst-node,multido}
\SpecialCoor
\psset{unit=1pt}

\def\FileName{node.data}% the data file

\makeatletter
\def\saveDataAsNodes{%
   \typeout{Open file \FileName}%
   \openin7=\FileName%
   \newcount\nMax\nMax=21\relax%         datarecords+1
   \newcount\nrepeat\nrepeat=1\relax%
   \loop%
         \def\NodeName{N\the\nrepeat}%
         \ifnum\nrepeat<\nMax
         \read7 to \Data
         \pnode(\Data){\NodeName}
         \typeout{\NodeName -> \Data}
         \advance\nrepeat by 1
   \repeat%
   \closein7%
}
%
\makeatother

\begin{document}

\begin{center}
\begin{pspicture}(-150,-150)(150,150)
   \saveDataAsNodes% must be inside the pspicture environment
%  \fileplot[linecolor=red,linewidth=1pt,linestyle=dashed]{\FileName}%
   \multido{\iA=1+1}{20}{
     \pscircle*[linecolor=blue](N\iA){10pt}}% Node: N#
\end{pspicture}
\end{center}

\end{document}


> 2) Is it possible to do linear (and other types of) regression with
> pstricks? 

sure, but we need someone who implements it ... ;-)


Herbert


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