Return root to tip distances (prdst) for ids
Examples
tree <- randTree(10)
getNdsPrdst(tree, ids = tree["tips"]) # return prdsts for all tips
#> t1 t10 t2 t3 t4 t5 t6 t7
#> 3.6567230 2.7647296 4.0935493 3.2651938 3.6791451 1.2224774 0.3579374 3.6393298
#> t8 t9
#> 3.0004659 2.6816396