Siblings shuffled for no reason

[magnusdv]

Hi,

I was wondering why, in the pedigrees below, sisters 3 and 4 are displayed in the wrong order. I understand that siblings are sometimes shuffled to improve the overall display, but in these symmetrical cases I cannot see any reason for doing so.

I think I have tracked the behaviour down to autohint(), but it is not clear to me what exactly this tries to optimize, nor why it is overzealous in my examples.

First example:

library(kinship2)
x = pedigree(id    = 1:6,
             dadid = c(0,0,1,1,1,1),
             momid = c(0,0,2,2,3,4),
             sex   = c(1,2,2,2,1,1))
plot(x)

Another example:

y = pedigree(id    = 1:7,
             dadid = c(0,0,1,1,0,5,5),
             momid = c(0,0,2,2,0,3,4),
             sex   = c(1,2,2,2,1,1,1))
plot(y)

^{Created on 2022-03-24 by the reprex package (v2.0.1)}

All the best,
Magnus