R help - Aug 2008 - lattice: add vertical lines in xyplot

Hi list,

This is a very basic question about lattice: I wish to add some  
vertical lines in each panel of a xyplot as demonstrated in this  
example:
> library(lattice)
>
> xx <- seq(1, 10, length=100)
> x <- rep(xx, 4)
> y <- c(cos(xx), sin(xx), xx, xx^2/10)
> fact <- factor(rep(c("cos", "sin", "id",
"square"), each=100))
> fact2 <- factor(rep(c("periodic", "not periodic"),
each=100))
>
> my.df <- data.frame(x=x, y=y, fact = fact, fact2 = fact2)
>
> head(my.df)
>
> xyplot(y~x | fact,  data = my.df,  groups= fact2) # this plots as  
> expected
>
> my.lines <- c(5, 6) # i want to draw these vertical lines, according  
> to the level of fact2
>
> xyplot(y~x | fact,  data = my.df,  groups= fact2,
> 	panel=function(x, y,subscripts,  ...) {
> 		panel.xyplot(x, y,subscripts,  ...)
> 		 panel.abline(v=my.lines[subscripts])}
> 	)
this gives me an error, but I don't understand the help for the panel  
function.

Alternatively, I tried in ggplot but here again, I get an error:
> p <- ggplot(my.df, aes(x, y)) +
> 	geom_path(aes(colour = fact)) +
> 		facet_grid(fact2 ~ fact) +
> 		 geom_vline(intercept = my.lines) # how do I select the relevant  
> one ?
> p
Many thanks,

baptiste

_____________________________

Baptiste Augui?

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag

On Thu, Aug 7, 2008 at 11:54 AM, baptiste auguie <ba208 at exeter.ac.uk>
wrote:
> Hi list,
>
> This is a very basic question about lattice: I wish to add some vertical
> lines in each panel of a xyplot as demonstrated in this example:
>
>> library(lattice)
>>
>> xx <- seq(1, 10, length=100)
>> x <- rep(xx, 4)
>> y <- c(cos(xx), sin(xx), xx, xx^2/10)
>> fact <- factor(rep(c("cos", "sin",
"id", "square"), each=100))
>> fact2 <- factor(rep(c("periodic", "not
periodic"), each=100))
>>
>> my.df <- data.frame(x=x, y=y, fact = fact, fact2 = fact2)
>>
>> head(my.df)
>>
>> xyplot(y~x | fact,  data = my.df,  groups= fact2) # this plots as
expected
>>
>> my.lines <- c(5, 6) # i want to draw these vertical lines, according
to
>> the level of fact2
>>
>> xyplot(y~x | fact,  data = my.df,  groups= fact2,
>>        panel=function(x, y,subscripts,  ...) {
>>                panel.xyplot(x, y,subscripts,  ...)
>>                 panel.abline(v=my.lines[subscripts])}
>>        )
>
> this gives me an error, but I don't understand the help for the panel
> function.
I think this is what you meant to do:

xyplot(y~x | fact,  data = my.df, groups= fact2,
       panel = function(x, y, subscripts, groups, ...) {
           panel.xyplot(x, y,
                        subscripts = subscripts,
                        groups = groups, ...)
           g <- unique(as.numeric(groups)[subscripts])
           panel.abline(v = my.lines[g])
       })

Another approach is

xyplot(y ~ x | fact,  data = my.df, groups= fact2,
       panel = panel.superpose,
       panel.groups = function(..., group.number) {
           panel.abline(v = my.lines[group.number])
           panel.xyplot(...)
       })

-Deepayan

> Alternatively, I tried in ggplot but here again, I get an error:
>
>> p <- ggplot(my.df, aes(x, y)) +
>>        geom_path(aes(colour = fact)) +
>>                facet_grid(fact2 ~ fact) +
>>                 geom_vline(intercept = my.lines) # how do I select the
>> relevant one ?
If you want a different line in each panel, you'll need to construct a
data frame - see the example at
http://had.co.nz/ggplot2/geom_abline.html for the basic idea.

Hadley


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