Make stat_interval provide width automatically for position='dodge'

[lindeloev]

I love stat_interval and would like to use it for some ordinary non-MCMC data. It says in the doc that it takes the position argument, but AFAICS, it does not respect it. I would expect two stat_intervals on this plot because of the grouping on x:

# Make some data which is two normals on x and bimodal on x2
df = data.frame(x = rep(c('A', 'B'), 30), 
                x2 = rep('A', 60),
                y = c(x = c(rnorm(30, 0), rnorm(30, 5))))

# Plot it, grouped by x
ggplot(df, aes(x=x2, y=y, group=x)) + 
    stat_interval(position='dodge')

Current result:

So there's only one interval, and that behaves weird in the edges (here, the top).

[mjskay]

Ah, yeah, good point. A workaround is to provide the width used to calculate the dodge manually with something like position = position_dodge(width = .1) (adjust the width to your taste), but some reasonable width should definitely be provided automatically based on the width of the geom.

[mjskay]

TODO:

• [x] add default width/height calculation for geom_interval(h)
• [ ] add default width/height calculation for geom_pointinterval(h) (might as well) this is more complex than I thought given usage in geom_eye / halfeye, punting on fixing geom_pointinterval until I do #84

[mjskay]

This is now fixed in the github version. If the default spacing is not to your taste, manually specifying it using position_dodge(width = XXX) also works (and will already work on the current CRAN version).

[lindeloev]

Awesome, thank you!

(Don't know why I didn't see the warning about `width in the current CRAN version)