On 09.08.2008 01:05 (UTC+1), Deepayan Sarkar wrote:
On Fri, Aug 8, 2008 at 2:38 PM, Rainer Hurling <[EMAIL PROTECTED]> wrote:
Dear community,
I am looking for a possibility to draw 'regression lines' instead of
'smooth' lines in grouped xyplots. The following code should give you a
small example of the data structure.
library(lattice)
data(Gcsemv, package = "mlmRev")
# Creates artificial grouping variable ...
Gcsemv$Groups <-
ifelse(as.numeric(as.character(Gcsemv$school))>65000,
"Group1", "Group2")
xyplot(written ~ course | gender, data = Gcsemv,
type = c("g", "p", "smooth"),
groups = Groups,
panel = function(x, y, ...) {
panel.xyplot(x, y, ...)
# Here I want to draw the regression lines
# panel.abline(x, y)
},
auto.key = list(space = 'right'))
Does this do what you want?:
Yes, exactly!
xyplot(written ~ course | gender, data = Gcsemv,
type = c("g", "p", "r"),
groups = Groups)
The problem with your approach is that the panel function you define
doesn't deal with groups. An easy workaround is to use
panel.superpose:
I knew that I had to look for a panel function dealing with groups, but
I had no clue how to declare.
xyplot(written ~ course | gender, data = Gcsemv,
type = c("g", "p"),
groups = Groups,
panel = panel.superpose,
panel.groups = function(x, y, ...) {
panel.xyplot(x, y, ...)
panel.lmline(x, y, ...)
},
auto.key = list(space = 'right'))
Both, type("r") and panel.groups() are fine for my problem. And with
panel.groups() I am able to write my own group functions, very nice. Now
I can start analyzing ... :-)
-Deepayan
Many thanks, also for your valuable book,
Rainer
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