[R] plotting regression line in with lattice

[matteo dossena]

Weidong, 
thanks for the suggestion, but i also need to show to which trt each point belongs to.
I had my problem solved by the way.
I've been told to add a group subscript object within the panel function, and than use panel.points to plot the original data as data points and panel.lines to draw the predicted regression line of the model.

cheers
m.



Il giorno 13 Jan 2012, alle ore 19:57, Weidong Gu ha scritto:

> Hi,
> 
> Since trt is a factor, you use it for indexing. try just delete in the code
> fill <- my.fill[combined$trt[subscripts]]
> 
> Weidong Gu
> 
> On Fri, Jan 13, 2012 at 11:30 AM, matteo dossena <m.dossena at qmul.ac.uk> wrote:
>> #Dear All,
>> #I'm having a bit of a trouble here, please help me...
>> #I have this data
>> set.seed(4)
>> mydata <- data.frame(var = rnorm(100),
>>                    temp = rnorm(100),
>>                    subj = as.factor(rep(c(1:10),5)),
>>                    trt = rep(c("A","B"), 50))
>> 
>> #and this model that fits them
>> lm  <- lm(var ~ temp * subj, data = mydata)
>> 
>> #i want to plot the results with lattice anf fit the regression line, predicted with my model, trough them
>> #to do so, I'm using this approach, outlined  "Lattice Tricks for the power useR" by D. Sarkar
>> 
>> temp_rng <- range(mydata$temp, finite = TRUE)
>> 
>> grid <- expand.grid(temp = do.breaks(temp_rng, 30),
>>                   subj = unique(mydata$subj),
>>                   trt = unique(mydata$trt))
>> 
>> model <- cbind(grid, var = predict(lm, newdata = grid))
>> 
>> orig <- mydata[c("var","temp","subj","trt")]
>> 
>> combined <- make.groups(original = orig, model = model)
>> 
>> 
>> xyplot(var ~ temp | subj,
>>      data = combined,
>>      groups = which,
>>      type = c("p", "l"),
>>      distribute.type = TRUE
>>      )
>> 
>> 
>> # so far every thing is fine, but, i also whant assign a filling to the data points for the two treatments trt=1 and trt=2
>> # so I have written this piece of code, that works fine, but when it comes to plot the regression line, it seems that type is not recognized by the panel function...
>> 
>> my.fill <- c("black", "grey")
>> 
>> plot <- with(combined,
>>       xyplot(var ~ temp | subj,
>>             data = combined,
>>             group = combined$which,
>>             type = c("p", "l"),
>>             distribute.type = TRUE,
>>             panel = function(x, y, ..., subscripts){
>>                        fill <- my.fill[combined$trt[subscripts]]
>>                        panel.xyplot(x, y, pch = 21, fill = my.fill, col = "black")
>>                        },
>>            key = list(space = "right",
>>                    text = list(c("trt1", "trt2"), cex = 0.8),
>>                    points = list(pch = c(21), fill = c("black", "grey")),
>>                    rep = FALSE)
>>                    )
>>     )
>> plot
>> 
>> #I've also tried to move type and distribute type within panel.xyplot, as well as subsseting the data in it panel.xyplot like this
>> 
>> plot <- with(combined,
>>       xyplot(var ~ temp | subj,
>>             data = combined,
>>             panel = function(x, y, ..., subscripts){
>>                        fill <- my.fill[combined$trt[subscripts]]
>>                        panel.xyplot(x[combined$which=="original"], y[combined$which=="original"], pch = 21, fill = my.fill, col = "black")
>>                        panel.xyplot(x[combined$which=="model"], y[combined$which=="model"], type = "l", col = "black")
>>                        },
>>            key = list(space = "right",
>>                    text = list(c("trt1", "trt2"), cex = 0.8),
>>                    points = list(pch = c(21), fill = c("black", "grey")),
>>                    rep = FALSE)
>>                    )
>>     )
>> plot
>> 
>> #but no success with that either...
>> #can anyone help me to get the predicted values plotted as a line instead of being points?
>> #really appricieate
>> #matteo
>> 
>> 
>> 
>> 
>> 
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>> 
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