[R] plotting regression line in with lattice

[Weidong Gu]

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
>
>
>
>
>
>        [[alternative HTML version deleted]]
>
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