- All Implemented Interfaces:
- RootedTreeMetric
public class CladeHeightMetric
extends java.lang.Object
implements RootedTreeMetric
For each clade_j in treeB, find the MRCA_j of the taxa in clade_j in treeA.
obviously, if clade_i exists in treeB then clade_i == MRCA_i.
Then find the sum of squares of the differences in height:
d = sqrt( sum across i[ (height(clade_i) - height(MRCA_i))^2 ] +
sum across j[ (height(clade_j) - height(MRCA_j))^2 ] )
The rationale is that if a clade moves then this includes the size of movement
across the MRCA node and down again. I.e., a clade that moves from one side
of the tree to the other scores the difference between the height of that node
and the root and back down to the height of the node in the other tree.
+---------A +---------A
+-+ +-+
| +---------B | |+--------B
+ ====> + ++
| +---------C | +--------C
+-+ |
+---------D +-----------D
height(tree1) tmrca(tree2) diff
AB 10 10 0
CD 10 12 2
ABCD 12 12 0
height(tree1) tmrca(tree2) diff
BC 9 12 3
ABC 10 10 0
ABCD 12 12 0
So the score is sqrt(2^2 + 3^2) = sqrt(13)
Scores much less than this:
+----------A +----------A
+ + +-+
| +----------B | | +-B
+ ====> + +--------+
| +---C | +-C
+--------+ |
+---D +------------D
height(tree1) tmrca(tree2) diff
AB 10 10 0
CD 4 12 8
ABCD 12 12 0
height(tree1) tmrca(tree2) diff
BC 2 12 10
ABC 10 10 0
ABCD 12 12 0
So the score is sqrt(8^2 + 10^2) = sqrt(164)
- Version:
- $Id$
- Author:
- Andrew Rambaut