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
#> 1.014101 1.906025 1.569293 2.024987 2.872199 2.330097 2.032350 1.027848
#> t8 t9
#> 2.152831 2.508484