panel.heights & panel.widths behaviour when unit length = 1

[davidhodge931]

Awesome new feature in setting panel widths and heights!

I am a big advocate for setting as much as possible theme/style stuff upfront.

So I'd be inclined to set panel heights and widths with set_theme.

Ideally I'd just do:

set_theme(
            theme_classic() +
            theme(
              panel.widths = unit(5, "cm"),
              panel.heights = unit(5, "cm")
            )

However , this won't work as I might have guessed when facetting because of the special behaviour.

Somewhat special behaviour occurs if you give a unit of length 1, but you have multiple panels. In that case, the total panel area is set, rather than the size of individual panels.

To get around this and ensure any amount of facetting would produce uniform panel sizes, I could:

set_theme(
            theme_classic() +
            theme(
              panel.widths = unit(rep(5, times=100), "cm"),
              panel.heights = unit(rep(5, times=100), "cm")
            )

I think what most people want is to easily set consistent panel sizes. So I wonder whether this special feature is worthwhile considering the potential confusion it'll cause? It seems like an edge case scenario, and also doesn't really align with intuitive meaning of the argument names..

Another way could be to have a panel.widths.total = NULL and panel.heights.total = NULL arguments ??

[teunbrand]

The size is recycled to fit the number of panels in that dimension, so if you have unit(c(5, 5), "cm"), you always have 5 cm panels, regardless of how many. We can mention this in the release blog, or document it, but I think having a total-width option is important, so I don't want to do away with it.

[davidhodge931]

What about having a panel.widths.total element? That would support the behavior required, and I think be more intuitive for the user

[teunbrand]

I'm not a fan of proliferating theme elements more than needed.

[davidhodge931]

Fair enough - thanks for all the ggplot2 work!