R：plot（）中的ylim和xlab / ylab对于grofit包不起作用

Question

I am trying to plot a growth spline for the variable "ipen" against "year" in this data. The code I am using is:

grofit <- read.csv('http://dl.dropbox.com/u/1791181/grofit.csv')
# install.packages(c("grofit"), dependencies = TRUE)
require(grofit)
growth = gcFitSpline(grofit$year, grofit$ipen)
plot(growth)

This works fine, and produces the plot below. But the problem is that (a) I can't change the default labels with xlab or ylab options, and (b) I can't change the scale of x-axis to be (0,100) with ylim=c(0,100) in the plot() statement. I could not find any pointers in the grofit() documentation. .

Answer 1

Don't directly use plot on the gcFitSpline result, but rather use str(growth) to explore the structure of the curve fit object and determine what you want to plot, or look at plot.gcFitSpline code (just type the name of the function without parentheses in the console and press Enter!)

For instance:

growth = gcFitSpline(grofit$year, grofit$ipen)

plot (grofit$year, grofit$ipen, pch=20, cex=0.8, col="gray", ylim=c(0, 100),
     ylab="Growth", xlab="Year", las=1)
points(growth$fit.time, growth$fit.data, t="l", lwd=2)

This gives:

Answer 2

Actually, I think the grofit documentation does have a pointer about this:

... Other graphical parameters may also passed as arguments [sic]. This has currently no effect and is only meant to fulfill the requirements of a generic function.

You may have to rewrite the plot.gcFitSpline function specific to the graphical parameters you want, but there might be a reason that the function is the way it is.

BTW, I'm not sure it's a great idea to give your data the same name as the package you're using.