Hi Henrique,
Sorry I wasn't very clear. I should have said that I think it's nice that
add=TRUE works for some things, like
plot(f)
plot(g, add=TRUE)
I think it's a convenient and simple way of adding things to a plot. But this
add=TRUE trick doesn't work for everything, and I think it would be convenient
if it did.
In the past, I've used
f <- function(x) x^2
X <- seq(0, 1, by=1/4)
plot(f, col="blue")
lines(X, f(X), col="red")
which I think is clumsy.
I didn't know about "new". Why is new back-to-front? If you specify
"new=TRUE", it does NOT create a new graph. Why does it require you
to specify empty xlab and ylab? Why doesn't this work:
f <- function(x) x^2
X <- seq(0, 1, by=1/4)
plot(f, col="blue")
plot(X, f(X), col="red", type="l", xlab="", ylab="", new=TRUE)
It seems like we can't solve the first problem with new=TRUE (that it's
back-to-front) without breaking backward compatibility. So I think add=TRUE
should be encouraged instead, as in my patch.
But, there is one extra thing to think about. Sometimes, it's useful to
have a for-loop for putting several functions on a graph. For example,
f <- function(a) function(x) a * x^2
plot.new()
for (a in c(1,2,3))
plot(f(a), add=TRUE, col=a)
This doesn't work well. For example, it doesn't draw the axes. Is there
a user-friendly way of doing this properly, short of
f <- function(a) function(x) a * x^2
plot(f(3), col=3)
for (a in 1:3)
plot(f(a), add=TRUE, col=a)
For instance, is there a command that can tell you if the axes have been
drawn? If there were, then you could do something like
f <- function(a) function(x) a * x^2
plot.new()
for (a in c(1,2,3))
plot(f(a), add=(TRUE & par("axes.already.drawn")), col=a)
Cheers,
Andrew
On Sun, Mar 09, 2008 at 12:08:59PM -0300, Henrique Dallazuanna wrote:
> I think you can use par(new = T) here:
>
> f <- function(x) x^2
> X <- seq(0, 1, by=1/4)
> plot(f, col="blue")
> par(new = T)
> plot(X, f(X), col="red", type="l", xlab="", ylab="")
>
> On 09/03/2008, Andrew Clausen <[EMAIL PROTECTED]> wrote:
> > Hi all,
> >
> > As long as I've used R, add=TRUE hasn't worked in contexts like this:
> >
> > f <- function(x) x^2
> > X <- seq(0, 1, by=1/4)
> > plot(f, col="blue")
> > plot(X, f(X), col="red", type="l", add=TRUE)
> >
> > I attached a fix for version 2.6.2.
> >
> > Cheers,
> > Andrew
> >
> >
>
>
> --
> Henrique Dallazuanna
> Curitiba-Paran?-Brasil
> 25? 25' 40" S 49? 16' 22" O
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