Return start and end ages for ids
from
when they first appear to when they split
Examples
tree <- randTree(10)
# all nodes but root
ids <- tree["nds"][tree["nds"] != tree["root"]]
getSpnsAge(tree, ids = ids, tree_age = getAge(tree))
#> spn start end
#> 1 n2 2.922474 2.4035720
#> 2 n3 2.403572 1.8779275
#> 3 n4 1.877927 1.4932074
#> 4 n5 2.403572 1.5981184
#> 5 n6 1.598118 0.7117128
#> 6 n7 1.493207 1.1008966
#> 7 n8 1.877927 1.3651629
#> 8 n9 1.598118 0.8856435