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 3.171887 2.1793670
#> 2 n3 3.171887 2.4629002
#> 3 n4 2.179367 1.4259549
#> 4 n5 2.462900 1.9475839
#> 5 n6 2.462900 1.8489569
#> 6 n7 1.848957 1.7952116
#> 7 n8 1.425955 0.9799168
#> 8 n9 1.795212 1.6482859