Hola!
It is somewhat inconvenient to use plot.function, when add=TRUE.
The following (miniscule) change makes it behave better:
plot.function <-
function (fn, from , to, xlim = NULL, ...)
{
if (!is.null(xlim)) {
if (missing(from))
from <- xlim[1]
if (missing(to))
to <- xlim[2]
}
curve(fn, from, to, xlim = xlim, ...)
}
The only change is that the default arguments fro from and to
are omitted. (curve() has better code to give sensible defaults)
But this makes problems for curve when add=FALSE is used.
The following miniscule changes to curve restores its behaviour when
add=FALSE: (changes only local to the delay() expression)
curve <-
function (expr, from, to, n = 101, add = FALSE, type = "l", ylab =
NULL,
log = NULL, xlim = NULL, ...)
{
sexpr <- substitute(expr)
if (is.name(sexpr)) {
fcall <- paste(sexpr, "(x)")
expr <- parse(text = fcall)
if (is.null(ylab))
ylab <- fcall
}
else {
if (!(is.call(sexpr) && match("x", all.vars(sexpr),
nomatch 0)))
stop("'expr' must be a function or an expression
containing
'x'")
expr <- sexpr
if (is.null(ylab))
ylab <- deparse(sexpr)
}
lims <- if (is.null(xlim))
delay({
if (add) {
pu <- par("usr")[1:2] } else
pu <- c(0,1)
if (par("xlog"))
10^pu
else pu
}, environment())
else xlim
if (missing(from))
from <- lims[1]
if (missing(to))
to <- lims[2]
lg <- if (length(log))
log
else paste(if (add && par("xlog"))
"x", if (add && par("ylog"))
"y", sep = "")
x <- if (lg != "" && "x" %in% strsplit(lg,
NULL)[[1]]) {
if (any(c(from, to) <= 0))
stop("`from' & `to' must be > 0 with
log=\"x\"")
exp(seq(log(from), log(to), length = n))
}
else seq(from, to, length = n)
y <- eval(expr, envir = list(x = x), enclos = parent.frame())
if (add)
lines(x, y, type = type, ...)
else plot(x, y, type = type, ylab = ylab, xlim = xlim, log = lg,
...)
}
Kjetil Halvorsen
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To:
r-devel-request@stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
