som_connection

Purpose

  To create a connection matrix of SOM 'hexa' and 'rect' negihborhoods

Syntax

  C = som_connection(S)

Description

  Creates a connection matrix of SOM 'hexa' and 'rect'
  neighborhoods. The connections are defined only in the upper
  triangular part to save some memory.

  Function SOM_UNIT_NEIGHS does the same thing, but also has values
  in the lower triangular. It is also slower, except for 
  'toroid' shape because in that case this function calls 

Som_unit_neighs...

Required input arguments

  S                 map topology 
    (map struct)    S.topol is used to build the matrix
    (topol struct)  topology information is used to build the matrix
    (cell array)    of form {lattice, msize, shape}, where
                     lattice: 'hexa' or 'rect'
                     msize  : 1x2 vector
                     shape  : 'sheet', 'cyl or 'toroid' 

Output arguments

  C (sparse)        munits x munits sparse matrix which describes 
                    nearest neighbor connections between units

Example

 C = som_connection('hexa',[3 4],'sheet');
 full(C)
 ans =

      0     1     0     1     0     0     0     0     0     0     0     0
      0     0     1     1     1     1     0     0     0     0     0     0
      0     0     0     0     0     1     0     0     0     0     0     0
      0     0     0     0     1     0     1     0     0     0     0     0
      0     0     0     0     0     1     1     1     1     0     0     0
      0     0     0     0     0     0     0     0     1     0     0     0
      0     0     0     0     0     0     0     1     0     1     0     0
      0     0     0     0     0     0     0     0     1     1     1     1
      0     0     0     0     0     0     0     0     0     0     0     1
      0     0     0     0     0     0     0     0     0     0     1     0
      0     0     0     0     0     0     0     0     0     0     0     1
      0     0     0     0     0     0     0     0     0     0     0     0

See also