Panel-based sizing of figures

[tfjaeger]

(Apologies if this has been raised and addressed before)

Despite all the marvels of ggplot2 and the many amazing extension packages, one thing that continues to consume a lot of time (or often is difficult to achieve at all) is the consistent sizing of figures for a publication. Specifically, I find that almost all the time my focus is on the relative sizing of panels (rather than the entire area of a figure) across figures. A common scenario is, for example, that I have the same multi-panel result plots across multiple figures. Another common scenario is that I'd like to plot a panel in Figure 1 at twice the width of Figure 2, etc. Critically, in all of these situations, my focus is on the panels rather than the entire figure.

I've searched across packages but I haven't found any easy way to create alignment in panel sizes across plots (I'd love to hear that I'm wrong!). Would it be possible, for example, to allow ggsave to save figures based on the panel size, or to provide other ways to easily express the dimensions of the panel itself. At the core of the issue that I'm trying to describe is that sizing seems to start by sizing the overall figure. The rest follows from that (incl. the panel size). But perhaps many researchers would find it more intuitive if sizing started with the panel? (plotting figures at 100% would then guarantee that all panels have proportional sizes as intended by the author).

Sorry, if this is all already solved or known to be unsolvable. In any case, thank you for all the amazing work on ggplot!!!