One option could be:

# Using Richard's example
boxplot(nmgml ~ factor(day, levels = do.call(seq,
as.list(range(girafe$day)))),
        data = girafe, xaxt = 'n')
axis(1, at = unique(girafe$day))

On Wed, May 12, 2010 at 10:30 AM, Mächler Marc Jaques <marcm@student.ethz.ch
> wrote:

> Dear R-Experts.
>
> I collected different datas about Nitrogen content (mg/ml) in Dung. The
> dung was eighter fresh (day=0) or had different ages (15,29,47) to observe
> nutrient changes over time.
>
> Now I like to draw a boxplot.
>
> boxplot(nmgml~day)
> abline((nmgml~day)
>
> The Problem is, that the boxplot considers the day values as groups and not
> as time series (neighter when the days are numeric or factors).
>
> The result is, that the regression line looks different as when I draw a
>  plot
> plot(nmgml~day)
> abline(nmgml~day)
>
> How can I reach that the boxplot's position on the x-axis is relative to
> the time value? (and the days are not just treated as groups)
>
> Data sample (Girafe-Dung)
>   day   nmgml
> 1   29 2.72655
> 2   29 2.48820
> 3   15 2.85945
> 4   15 2.58915
> 5   15 2.88345
> 6   15 2.66675
> 7   47 3.29125
> 8   15 2.44085
> 9   29 2.43065
> 10  29 2.43425
> 11  29 2.42705
> 12   0 1.12350
> 13  15 5.10310
> 14  15 0.99880
> 15   0 2.22350
> 16  47 2.18290
> 17  47 2.21570
> 18  47 2.46450
> 19  29 2.53350
> 20  47 2.78550
> 21  47 3.06920
> 22   0 2.65660
> 23   0 2.16650
> 24   0 2.20620
> 25   0 1.91870
> 26   0 2.45160
> 27   0 2.35980
> 28   0 1.99900
> 29   0 2.16300
> 30  15 2.00460
> 31  15 2.56220
> 32  47 2.38650
> 33  29 2.65820
> 34  29 2.47670
> 35  47 2.23770
> 36  29 2.40080
> 37  47 2.12650
> 38  29 2.35950
>
> I really apreciate your help
>
> Sincerly...
>
> MJMaechler (Zurich, Switzerland)
> ______________________________________________
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> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>



-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O

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