On Fri, Mar 11, 2011 at 12:28 AM, <boris.vasil...@forces.gc.ca> wrote: > Good afternoon, > > I am trying to create a plot where the bottom and top axes have the same > scale but different tick marks. I tried user-defined xscale.component > function but it does not produce desired results. Can anybody suggest > where my use of xscale.component function is incorrect? > > For example, the code below tries to create a plot where horizontal axes > limits are c(0,10), top axis has ticks at odd integers, and bottom axis > has ticks at even integers. > > library(lattice) > > df <- data.frame(x=1:10,y=1:10) > > xscale.components.A <- function(...,user.value=NULL) { > # get default axes definition list; print user.value > ans <- xscale.components.default(...) > print(user.value) > > # start with the same definition of bottom and top axes > ans$top <- ans$bottom > > # - bottom labels > ans$bottom$labels$at <- seq(0,10,by=2) > ans$bottom$labels$labels <- paste("B",seq(0,10,by=2),sep="-") > > # - top labels > ans$top$labels$at <- seq(1,9,by=2) > ans$top$labels$labels <- paste("T",seq(1,9,by=2),sep="-") > > # return axes definition list > return(ans) > } > > oltc <- xyplot(y~x,data=df, > > scales=list(x=list(limits=c(0,10),at=0:10,alternating=3)), > xscale.components=xscale.components.A, > user.value=1) > print(oltc) > > The code generates a figure with incorrectly placed bottom and top > labels. Bottom labels "B-0", "B-2", ... are at 0, 1, ... and top labels > "T-1", "T-3", ... are at 0, 1, ... When axis-function runs out of > labels, it replaces labels with NA. > > It appears that lattice uses top$ticks$at to place labels and > top$labels$labels for labels. Is there a way to override this behaviour > (other than to expand the "labels$labels" vector to be as long as > "ticks$at" vector and set necessary elements to "")?
Well, <top|bottom>$ticks$at is used to place the ticks, and $labels$at is used to place the labels. They should typically be the same, but you have changed one and not the other. Everything seems to work if you set $ticks$at to the same values as $labels$at: ## - bottom labels + ans$bottom$ticks$at <- seq(0,10,by=2) ans$bottom$labels$at <- seq(0,10,by=2) ans$bottom$labels$labels <- paste("B",seq(0,10,by=2),sep="-") ## - top labels + ans$top$ticks$at <- seq(1,9,by=2) ans$top$labels$at <- seq(1,9,by=2) ans$top$labels$labels <- paste("T",seq(1,9,by=2),sep="-") > Also, can user-parameter be passed into xscale.components() function? > (For example, locations and labels of ticks on the top axis). In the > code above, print(user.value) returns NULL even though in the xyplot() > call user.value is 1. No. Unrecognized arguments are passed to the panel function only, not to any other function. However, you can always define an inline function: oltc <- xyplot(y~x,data=df, scales=list(x=list(limits=c(0,10), at = 0:10, alternating=3)), xscale.components = function(...) xscale.components.A(..., user.value=1)) Hope that helps (and sorry for the late reply). -Deepayan ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.