AW: [R] How to improve the quality of curve/line plots?

[Arne Henningsen]

On Friday 24 September 2004 09:35, Wolf, Michael wrote:
> Thanks for the tip using a smoothing technique before plotiing in order to
> get a curve instead of a line connecting the observations.
>
> But that's not the solution for my main problem with the "unclean" line 
plot. In order to show my problem let's take this simple example:
> > xval <- c(1, 2, 3, 4, 5, 6, 7, 8)
> > yval <- c(10, 30, 40, 50, 70, 90, 100, 110)
> > plot (xval, yval, type="l")
>
> If you look to the result in the graphic window you will see that the line
> seems to exist of many points between the observations; e. g. between
> xval=1 and xval=2 the line contains 8 or more sublines. Perhaps, you can
> also observe a break of the line at xval=4. That's what I call an "unclean
> line".

You can increase the linewidth with, e.g.:
plot (xval, yval, type="l", lwd=2)

> Even if you try to export the plot with the png command you can observe the
> same phenomenon. The line has not an exact appearance like Excel diagram
> plots. If there are no other techniques to get better line plots it seems
> to be a problem of the graphic output!?

And you can increase the resolution, e.g.:
png( "myplot.png", 1000, 1000 )

Best wishes,
Arne

> Michael Wolf
>
> -----Ursprüngliche Nachricht-----
> Von: Uwe Ligges [mailto:ligges at statistik.uni-dortmund.de]
> Gesendet: Freitag, 24. September 2004 09:00
> An: Wolf, Michael
> Cc: r-help at stat.math.ethz.ch
> Betreff: Re: [R] How to improve the quality of curve/line plots?
>
> Wolf, Michael wrote:
> > Dear list,
> >
> > I'm using the windows version of R. When plotting a curve or a line for
> > time series with annual data , e. g. GDP growth 1991-2003, the line seems
> > to exist of a lot of smaller lines. Printing the results the curves and
> > lines seems to be "unclean" (because of using small resolution bitmaps?).
> > Comparing the result of R with the same results of Excel the lines in
> > excel seems to havve a higher qualitiy. In Excel you also can produce
> > curves instead of lines.
> >
> > Are there any possibilities how to improve the quality of the plots in R?
> > How can R be influenced to plot "clean" lines with a higher resolution on
> > the screen (I think it's not a question of the pdf- or png command.).
> > Perhaps, it's a problem of the graphical possibilites of R because the
> > most line plots which can be seen on the web have these problems.
>
> Can you specify an example please? I cannot remember any "unclean" plot.
> In particular, no bitmaps are used to render graphics in R.
>
> What I guess is that you have a line plot and each observation is connected
> with the subsequent one by a line. If you want to smooth it (and you think
> smoothing is appropriate here), you have to apply a smoothing technique
> before plotting.
>
> Uwe Ligges
>
> > Thanks,
> >
> > Dr. Michael Wolf
> > Bezirksregierung Münster
> > Dezernat 61
> > Domplatz 1-3    48161 Münster
> > Tel.:   ++ 49 (02 51) / 4 11 - 17 95
> > Fax.:   ++ 49 (02 51) / 4 11 - 8 17 95
> > E-Mail: michael.wolf at bezreg-muenster.nrw.de
> >
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-- 
Arne Henningsen
Department of Agricultural Economics
University of Kiel
Olshausenstr. 40
D-24098 Kiel (Germany)
Tel: +49-431-880 4445
Fax: +49-431-880 1397
ahenningsen at agric-econ.uni-kiel.de
http://www.uni-kiel.de/agrarpol/ahenningsen/