R help - Mar 2010 - filled.contour formatting questions

Hello, I'm having some trouble getting things to look as I want with
filled.contour.

1.  My first issue is that I am unable to add line segments to my plot where
I want them.  Using the rug pattern example:
x <- y <- seq(-4*pi, 4*pi, len = 27);
r <- sqrt(outer(x^2, y^2, "+"));
filled.contour(cos(r^2)*exp(-r/(2*pi)));
segments(0.2,0.2,1,0.2);
The line segment is not found in relation to the x-axis but is seemingly
squished over by the color bar.

If I try to achieve the line this way:
filled.contour(cos(r^2)*exp(-r/(2*pi)),plot.axes={lines(c(0.2,1),c(0.2,0.2))})
Now when I add the axis back it is misaligned.
axis(1).

2. Secondly I'm finding the literature difficult to understand on how to
make a nice color scheme.  Below is a nice scheme I found from an example,
except I don't understand why the scale seems to cycle into blue again for
larger values, even though I think I am setting the number of levels of
colors and contour levels to be equal.  Basically I want reds for the
highest values and blues for the lowest:
filled.contour(cos(r^2)*exp(-r/(2*pi)),nlevels=25,col=hsv(h=seq(from=.7,to=0,length=25)))

3.  I'm used to working with matlab where it was simple to make the color
scale the same on multiple figures using caxis().  However I don't see this
option for filled.contour (possibly it exists for levelplot() but I was
having even less success understanding that one).  I only see the option to
set the number of levels which doesn't really accomplish what I want for
plots that are going to have widely varying limits.

Thanks very much for any help, John.

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On 03/23/2010 12:48 PM, John K. Williams wrote:
> Hello, I'm having some trouble getting things to look as I want with
> filled.contour.
>
> 1.  My first issue is that I am unable to add line segments to my plot
where
> I want them.  Using the rug pattern example:
> x<- y<- seq(-4*pi, 4*pi, len = 27);
> r<- sqrt(outer(x^2, y^2, "+"));
> filled.contour(cos(r^2)*exp(-r/(2*pi)));
> segments(0.2,0.2,1,0.2);
> The line segment is not found in relation to the x-axis but is seemingly
> squished over by the color bar.
>
> If I try to achieve the line this way:
>
filled.contour(cos(r^2)*exp(-r/(2*pi)),plot.axes={lines(c(0.2,1),c(0.2,0.2))})
> Now when I add the axis back it is misaligned.
> axis(1).
>
> 2. Secondly I'm finding the literature difficult to understand on how
to
> make a nice color scheme.  Below is a nice scheme I found from an example,
> except I don't understand why the scale seems to cycle into blue again
for
> larger values, even though I think I am setting the number of levels of
> colors and contour levels to be equal.  Basically I want reds for the
> highest values and blues for the lowest:
>
filled.contour(cos(r^2)*exp(-r/(2*pi)),nlevels=25,col=hsv(h=seq(from=.7,to=0,length=25)))
>
> 3.  I'm used to working with matlab where it was simple to make the
color
> scale the same on multiple figures using caxis().  However I don't see
this
> option for filled.contour (possibly it exists for levelplot() but I was
> having even less success understanding that one).  I only see the option to
> set the number of levels which doesn't really accomplish what I want
for
> plots that are going to have widely varying limits.
>
Hi John,
I'm not sure that this is what you want, but the examples for the barp 
function in the plotrix package include one for a color scale that 
extends beyond the values that are to be plotted. That is, you can 
specify the range of the color scale regardless of the actual values.

Jim