plot.type="persp", plot=FALSE: image plotted

[Derek-Jones]

t=visreg2d(..., plot.type="persp", plot=FALSE)

plot(t)

results in an image being plotted, i.e., acts as-if plot.type="image"

[pbreheny]

plot.type is an argument to plot.visreg, not visreg. For this to work, you would have to submit

t <- visreg2d(..., plot=FALSE)
plot(t, plot.type="persp")

[Derek-Jones]

Thanks for such a prompt response.

This behavior is user unfriendly. Why not just have visreg2d return the information so plot can make use of it (also for the axis labels)?

The documentation does not specify that image is used unless explicitly specified (not that I had previously read the documentation)

[pbreheny]

1. This behavior is user unfriendly. Why not just have visreg2d return the information so plot can make use of it (also for the axis labels)?

I see what you're saying, but I don't agree. Part of the value of allowing the user to break the plot up into two steps is to separate the construction of the object from how it's plotted:

fit <- lm(Ozone ~ Solar.R + Wind + Temp, data=airquality)
v <- visreg(fit, 'Wind', plot=FALSE)
plot(v)
plot(v, gg=TRUE)
plot(v, line.par=list(col='red'))

Options that change the appearance of the plot need to be passed to the plotting function...to me, that seems straightforward.

2. The documentation does not specify that image is used

Yes it does, see ?plot.visreg2d.

[Derek-Jones]

Yes, plot should be able to override previously specified values. But why force users down this path? It also makes the use of plot inflexible.

Requiring that plot duplicate the presentation information present in the call to visreg2d ties that call to plot down to always plotting the value returned by on call to visreg2d.

It means that the decision about what to plot cannot be decided at runtime, or by passing a value to a function.

The documentation requires me to switch my brain on, rather than rely on default assumptions.

[pbreheny]

1. There is no inflexibility; users are not required to match or duplicate anything in calls to plot.

2. Specifying

visreg2d(..., plot.type="persp", plot=FALSE)

is not meaningful. You're telling visreg not to plot anything, but also telling it the type of nothing it should plot.

3. The basic use of visreg/visreg2d is

visreg(fit, 'var', options)

which works fine and does not require users to "switch their brain on" or carefully read the documentation. The package also allows users to break this up into two steps if they are trying to accomplish something advanced that requires additional customization:

v <- visreg(fit, 'var', plot=FALSE)
plot(v)

It seems reasonable to me that if you're trying to accomplish advanced customization, that you would probably want to read the documentation. Can I ask what you're trying to accomplish by splitting the plotting into two separate steps?

[Derek-Jones]

I'm working on a book and am using Asciidoc, preprocessing files with the ascii package to generate the pdfs.

For whatever reason, pdfs don't appear unless they are generated using a plot function. At least they don't for the lattice functions and a few other packages (I have not tried with visreg, I just assumed).

My working habit is to tune interactively and then add a call to plot last. So I got caught out by this behavior, which I have not seen in other packages.

[pbreheny]

Ah, I see; that makes more sense now. Yes, certain packages like lattice and ggplot2 don't plot inside certain environments unless there's an explicit request to plot:

library(lattice)
f <- function() {
  xyplot(lat ~ long | cut(Depth, 5), data = quakes)  
}
y <- f()  # Doesn't plot

# All of these plot
y
print(y)
plot(y)

However, this doesn't happen with visreg:

library(visreg)
fit <- lm(Ozone ~ Solar.R + Wind + Temp, data=airquality)
f <- function() {
  visreg(fit, 'Wind', by='Temp')
}
y <- f()  # Plots, even though a lattice plot is being produced

ggplot2 plots(gg=TRUE) are an exception, though -- there, the gg object is returned because it is possible to add things to it or customize it prior to plotting.

[Derek-Jones]

if (a)
    X=visreg(fit, 'Wind', by='Temp', xlab="Wind info")
 else
    X=visreg(fit, 'Temp', by='Wind, xlab="Temp info")

 # Some code

 plot(X, xlab="Wind or Temp info")