Combining geoms & scales

[Ryan Hope]

I am working on a R package for eyetracking reasearch and in it I provide some functions to visual data with ggplot2. Some of the visualizations are stand alone plots but others work well as layers that could be combined with other plots. I've created some "custom" geoms by simply wrapping pre-existing geoms in a function so that I can transform in input into ggplot friendly arguments. This works fine for most cases but I have run into a few situations where I would like to combine 2 geoms into one. For example, I would like to do something like this:

geom_grid <- function() {

 geom_hline() + geom_vline()

}

which obviously throws a "non-numeric argument to binary operator" error. The same thing goes for creating a function to set both x and y scales with one function. Is there an easy way to do this?

--
Ryan Hope, M.S.
CogWorks Lab
Cognitive Science Department
Rensselaer Polytechnic Institute

[Brian Diggs]

On 5/18/2013 5:56 AM, Ryan Hope wrote:
> I am working on a R package for eyetracking reasearch and in it I provide
> some functions to visual data with ggplot2. Some of the visualizations are
> stand alone plots but others work well as layers that could be combined
> with other plots. I've created some "custom" geoms by simply wrapping
> pre-existing geoms in a function so that I can transform in input into
> ggplot friendly arguments. This works fine for most cases but I have run
> into a few situations where I would like to combine 2 geoms into one. For
> example, I would like to do something like this:
>
> geom_grid <- function() {
> geom_hline() + geom_vline()
> }

geom_grid <- function() {
c(geom_hline(), geom_vline())
}

Or in a complete example:

geom_grid <- function(v = 0) {
c(geom_hline(yintercept=v), geom_vline(xintercept=v))
}

ggplot(data.frame(x=rnorm(20), y=rnorm(20)), aes(x,y)) +
geom_point() +
geom_grid() +
geom_grid(1)

> which obviously throws a "non-numeric argument to binary operator" error.
> The same thing goes for creating a function to set both x and y scales with
> one function. Is there an easy way to do this?
>


--

Brian S. Diggs, PhD
Senior Research Associate, Department of Surgery
Oregon Health & Science University

[Ryan Hope]

Awesome, this seems to work great for geoms but not for scales :/

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[thomas kern]

try

sc = function(){
  list(scale_x_continuous(breaks=1:10), scale_y_continuous(breaks=100:101))

[Ryan Hope]

Using list() works for both geoms and scales, thanks Brian!