SimplexTree.contract

SimplexTree.SimplexTree.contract(pair)

Performs an pair contraction.

This function performs an pair contraction: given a pair of vertices (va, vb), vertex vb is said to contract to va if vb is removed from the complex and the link of va is augmented with the link of vb.

Some notes about pair are in order: - pair is not sorted like other simplex inputs - The second vertex is always contracted to the first - pair need not be an existing simplex (edge) in the complex - Contraction is not symmetric.

Parameters

Name	Type	Description	Default
pair	Collection	pair to contract	required

Returns

Name	Type	Description
	None	whether the pair was contracted

Examples

from simplextree import SimplexTree
st = SimplexTree([[0,1,2]])
st.print()

0 1 2 0 0 1 0
      1 2 2 1
            2

st.contract([0,2])
st.print()

0 1 0
    1