Ok...I realized that if I don't wish to compare the groupings directly

i can plot the groups as separate panels, which is a much more simple
solution, but doesn't necessarily give the same effect.

xyplot(y+y2 ~ x | grp, dat)


On Sun, Feb 14, 2010 at 3:19 PM, Dennis Murphy <djmuser@gmail.com> wrote:

> Hi:
>
> Here's one approach: the idea is to essentially stack the responses in both
> data sets, create a factor that identifies the stacked variables, merges
> the data
> together and then combines 'variable' and 'grp' from the merged data frame
> into a single factor for use as the groups = element in xyplot. (Got all
> that?)
>
> library(lattice)
> library(reshape)
> # use the melt function of reshape to stack the responses and create an
> # identifier (variable) for them. The responses themselves are put into a
> # variable named 'value'. id.vars are kept separate, the others are stacked
> # into a variable identifier called 'variable' and the vector of values
> called
> # 'values'...
> Dat <- melt(dat, id.vars = c('x', 'grp'))
> Dat2 <- melt(dat2, id.vars = c('x', 'grp'))
> Dat3 <- rbind(Dat, Dat2)     # concatenate the two data frames
> Dat3$gv <- with(Dat3, paste(variable, grp, sep = ""))  # combine factors
>
> xyplot(value ~ x, data = Dat3, groups = gv, type = "l")
>
> There are more elegant ways to create the grouping factor, which you may
> need if you intend to create a 'nice' legend, but at this level it works.
>
> HTH,
> Dennis
>
> On Sun, Feb 14, 2010 at 12:44 PM, Pat Schmitz <pschmitz@illinois.edu>wrote:
>
>> All
>>
>> I want to overlay two variables on the same plot following their
>> appropriate
>> grouping.  I have attempted to use subscripting in panel with
>> panel.xyplot,
>> but I can't get the grouping to follow into the panel...here is an
>> example...
>>
>>
>> dat<-data.frame(
>> y= log(1:10),
>> y2=10:19,
>>  x=1:10,
>> grp = as.factor(1)
>> )
>>
>> dat2<-data.frame(
>>  y= log(10:19),
>> y2= 20:29,
>> x=1:10,
>>  grp = as.factor(c(2))
>> )
>>
>> dat<-rbind(dat, dat2)
>>
>> # Here I plot both response variables on y axis by the same x
>> xyplot(y2 ~ x, dat, groups=grp, type="l")
>> xyplot(y ~ x, dat, groups=grp, type="l")
>>
>> # I want to overlay both in the same plot to compare
>> xyplot(y~ x, dat,
>>  groups = grp,
>> ylim = c(0,40),
>> panel=function(x,y,subscripts, groups,...){
>>  panel.xyplot(x, y, type="l")
>> panel.xyplot(dat$x[subscripts], dat$y2[subscripts],type="l")
>>  }
>> )
>>
>>
>> Thanks
>>
>> --
>> Patrick Schmitz
>> Graduate Student
>> Plant Biology
>> 1206 West Gregory Drive
>> RM 1500
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help@r-project.org mailing list
>> 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.
>>
>
>


-- 
Patrick Schmitz
Graduate Student
Plant Biology
1206 West Gregory Drive
RM 1500

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