unit comparison with arithmetic units

[baptiste]

compare.unit fails with arithmetic units:

s1 <- max(grobWidth(textGrob("a")), grobWidth(textGrob("1")))
s2 <- max(grobWidth(textGrob("a")), grobWidth(textGrob("2")))
gtable:::compare.unit(s1, s2, pmin)
unit.pmin(s1, s2)

Better use unit.pmax and unit.pmin I think.

[hadley]

Is there a reason you modified rbind rather than fixing the problem in compare.unit?

[baptiste]

not really; on a practical side it meant that i only needed to change one function (outside of the namespace). Also, I thought compare.units might have had a more general function (beyond pmin and pmax). Essentially, compare.units becomes redundant, unless it has other uses?

That said, I'm happy to change compare.units instead.

[hadley]

The problem with unit.pmin and unit.pmax is that they return units which are computed at render-time, which tends to be slow.

[baptiste]

I'm not sure there's an alternative around that; if gtable is to be a general layout framework you'll always have these complex units that need to be computed on-the-fly (I needed them for the tableGrob function I was developing). Is it really so slow that it matters?

[baptiste]

any updates on this, and gtable development in general? So many people request on SO how to align two plots / gtables, and this particular issue is the only thing that prevents rbind_gtable and cbind_gtable from being the best answer.

[hadley]

We're busy on other projects at the moment, but will hopefully come back to this in the not too distant future.