Dear List

I want to plot multiple time series (several outcomes) with dates at intervals on the x axis and a legend.

Is it possible to use axis.Date to get dates, at intervals in  my case, on the x axis of a (multiple) time series plot.
The axis.Date in the code below doesn't produce any dates on the x axis. (The difference outcome measures are all variable outcome in dataframe speclong and the  different groups correspond to different values of the variable time with values 1 to 8)

But the same axis.Date command gives x axis Dates perfectly if following an ordinary plot command. So I suppose I could do that and add time series for successive time series using lines( but then I wouldn't have a legend or I'd have to create one "manually"

Many thanks for any advice

Bernard

speclong
          Date time     outcome id
1.1 1998-01-29    1 8.11879e-13  1
2.1 1998-02-17    1 9.11297e-13  2
3.1 1998-03-20    1 4.95558e-13  3
4.1 1998-05-07    1 4.34171e-13  4
5.1 1998-05-26    1 2.41658e-13  5
6.1 1998-06-05    1 4.89529e-13  6
....
82.8 2005-07-15    8 2.37023e-11 82
83.8 2005-08-23    8 3.52766e-11 83
84.8 2005-09-08    8 1.98099e-11 84
85.8 2005-10-18    8 2.93576e-11 85
86.8 2005-11-18    8 6.30531e-11 86
87.8 2005-12-01    8 5.71245e-11 87
> interaction.plot(speclong$Date,speclong$time,speclong$outcome,log="y",xaxt="n",col=rainbow(8) )
> axis.Date(1,at=(as.Date("1998-01-01") +c(0:7)*365.25),format="%d/%m/%y", las=2)
>
> sessionInfo()
R version 2.9.0 (2009-04-17)
i386-pc-mingw32

locale:
LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

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