[R] xyplot type="l"

[David Winsemius]

On Apr 15, 2012, at 11:54 AM, Peter Ehlers wrote:

> On 2012-04-15 03:19, Eiko Fried wrote:
>> Probably a stupidly simple question, but I wouldn't know how to  
>> google it:
>>
>> xyplot(neuro ~ time | UserID, data=data_sub)
>>
>> creates a proper plot.
>>
>> However, if I add
>> type = "l"
>> the lines do not go first through time1, then time2, then time3 etc  
>> but in
>> about 50% of all subjects the lines go through points seemingly  
>> random
>> (e.g. from 1 to 4 to 2 to 5 to 3).
>> The lines always start at time point 1, though.
>>
>> Defining "time" as factor or ordered doesn't change this.
>> "neuro" is a numerical variable.
>>
>> It's probably some beginner's mistake, but I don't seem to be able  
>> to solve
>> it.
>
> See if this gives a clue:
>
>    library(lattice)
>    xyplot(Sepal.Length ~ Sepal.Width | Species, type = 'l',
>           data = iris)
>    ord <- with(iris, order(Sepal.Width))
>    iris2 <- iris[ord,]
>    xyplot(Sepal.Length ~ Sepal.Width | Species, type = 'l',
>           data = iris2)
>
I hope Peter doesn't take offense when I opine that the improved  
version remains an ugly plot. Better would be:

xyplot(Sepal.Length ~ Sepal.Width | Species,
           panel=function(x,y, ...){
                    panel.xyplot(x,y, ...)
                    panel.loess(x,y)},
           data = iris)

OR:

xyplot(Sepal.Length ~ Sepal.Width | Species,
           panel=function(x,y, ...){
                    panel.xyplot(x,y,...)
                    panel.lmline(x,y)},
           data = iris)
-- 
David Winsemius, MD
West Hartford, CT