This started when I discovered that scatter.smooth (R 2.1.0) has an
undocumented ability to use a formula as the first argument. Then I
discovered the xy.coords function, which seems like a natural fit and a
way to unify scatter.smooth with other plotting functions, so I offer here
a revised version of scatter.smooth that uses the xy.coords function.
scatter.smooth <- function (x, y=NULL, span = 2/3, degree = 1,
family = c("symmetric", "gaussian"),
xlab = NULL,
ylab = NULL,
ylim = range(y, prediction$y, na.rm = TRUE),
evaluation = 50, ...) {
xlabel <- if (!missing(x))
deparse(substitute(x))
ylabel <- if (!missing(y))
deparse(substitute(y))
xy <- xy.coords(x, y, xlabel, ylabel)
x <- xy$x
y <- xy$y
xlab <- if(is.null(xlab)) xy$xlab
else xlab
ylab <- if(is.null(ylab)) xy$ylab
else ylab
# if (inherits(x, "formula")) {
# if (length(x) < 3)
# stop("need response in formula")
# thiscall <- match.call()
# thiscall$x <- x[[3]]
# thiscall$y <- x[[2]]
# return(invisible(eval(thiscall, sys.parent())))
# }
prediction <- loess.smooth(x, y, span, degree, family, evaluation)
plot(x, y, ylim = ylim, xlab = xlab, ylab = ylab, ...)
lines(prediction)
invisible()
}
1. I commented out some existing code and my revisions appear before the
commented block.
2. The argument list has changed slightly. The original arguments were:
y
xlab=deparse(substitute(x))
ylab=deparse(substitute(y))
3. With the suggested change, the following examples now work as one
would expect
attach(cars)
scatter.smooth(speed,dist,main="dist,speed")
scatter.smooth(speed,dist,main="dist,speed",xlab="",ylab="")
scatter.smooth(cars,main="cars")
scatter.smooth(cars,main="cars",xlab="Speed",ylab="Distance")
scatter.smooth(dist~speed,main="dist~speed")
scatter.smooth(dist~speed,main="dist~speed",xlab="")
scatter.smooth(dist~speed,main="dist~speed",ylab="")
4. If this revision is accepted, the help page for scatter.smooth should
probably be updated, perhaps using the same definition of the x,y
arguments in the plot.default help page.
Best,
Kevin Wright
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