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comparison toolboxes/MIRtoolbox1.3.2/somtoolbox/som_unit_neighs.m @ 0:e9a9cd732c1e tip

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first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
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1 function Ne1 = som_unit_neighs(topol,lattice,shape)
2
3 %SOM_UNIT_NEIGHS Matrix indicating units in 1-neighborhood for each map unit.
4 %
5 % Ne1 = som_unit_neighs(topol,[lattice],[shape])
6 %
7 % Ne1 = som_unit_neighs(sTopol);
8 % Ne1 = som_unit_neighs(sMap.topol);
9 % Ne1 = som_unit_neighs([10 4], 'hexa', 'cyl');
10 % Ne1 = som_unit_neighs(msize, 'rect', 'toroid');
11 %
12 % Input and output arguments ([]'s are optional):
13 % topol topology of the SOM grid
14 % (struct) topology or map struct
15 % (vector) the 'msize' field of topology struct
16 % [lattice] (string) map lattice, 'rect' by default
17 % [shape] (string) map shape, 'sheet' by default
18 %
19 % Ne1 (matrix, size [munits munits]) a sparse matrix
20 % indicating the map units in 1-neighborhood
21 % by value 1 (note: the unit itself also has value 0)
22 %
23 % For more help, try 'type som_unit_neighs' or check out online documentation.
24 % See also SOM_NEIGHBORHOOD, SOM_UNIT_DISTS, SOM_UNIT_COORDS, SOM_CONNECTION.
25
26 %%%%%%%%%%%%% DETAILED DESCRIPTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
27 %
28 % som_unit_neighs
29 %
30 % PURPOSE
31 %
32 % Find the adjacent (in 1-neighborhood) units for each map unit of a SOM
33 % based on given topology.
34 %
35 % SYNTAX
36 %
37 % Ne1 = som_unit_neighs(sMap);
38 % Ne1 = som_unit_neighs(sM.topol);
39 % Ne1 = som_unit_neighs(msize);
40 % Ne1 = som_unit_neighs(msize,'hexa');
41 % Ne1 = som_unit_neighs(msize,'rect','toroid');
42 %
43 % DESCRIPTION
44 %
45 % For each map unit, find the units the distance of which from
46 % the map unit is equal to 1. The distances are calculated
47 % along the map grid. Consider, for example, the case of a 4x3 map.
48 % The unit ('1' to 'C') positions for 'rect' and 'hexa' lattice (and
49 % 'sheet' shape) are depicted below:
50 %
51 % 'rect' lattice 'hexa' lattice
52 % -------------- --------------
53 % 1 5 9 1 5 9
54 % 2 6 a 2 6 a
55 % 3 7 b 3 7 b
56 % 4 8 c 4 8 c
57 %
58 % The units in 1-neighborhood (adjacent units) for unit '6' are '2','5','7'
59 % and 'a' in the 'rect' case and '5','2','7','9','a' and 'b' in the 'hexa'
60 % case. The function returns a sparse matrix having value 1 for these units.
61 % Notice that not all units have equal number of neighbors. Unit '1' has only
62 % units '2' and '5' in its 1-neighborhood.
63 %
64 % REQUIRED INPUT ARGUMENTS
65 %
66 % topol Map grid dimensions.
67 % (struct) topology struct or map struct, the topology
68 % (msize, lattice, shape) of the map is taken from
69 % the appropriate fields (see e.g. SOM_SET)
70 % (vector) the vector which gives the size of the map grid
71 % (msize-field of the topology struct).
72 %
73 % OPTIONAL INPUT ARGUMENTS
74 %
75 % lattice (string) The map lattice, either 'rect' or 'hexa'. Default
76 % is 'rect'. 'hexa' can only be used with 1- or
77 % 2-dimensional map grids.
78 % shape (string) The map shape, either 'sheet', 'cyl' or 'toroid'.
79 % Default is 'sheet'.
80 %
81 % OUTPUT ARGUMENTS
82 %
83 % Ne1 (matrix) sparse matrix indicating units in 1-neighborhood
84 % by 1, all others have value 0 (including the unit itself!),
85 % size is [munits munits]
86 %
87 % EXAMPLES
88 %
89 % Simplest case:
90 % Ne1 = som_unit_neighs(sTopol);
91 % Ne1 = som_unit_neighs(sMap.topol);
92 % Ne1 = som_unit_neighs(msize);
93 % Ne1 = som_unit_neighs([10 10]);
94 %
95 % If topology is given as vector, lattice is 'rect' and shape is 'sheet'
96 % by default. To change these, you can use the optional arguments:
97 % Ne1 = som_unit_neighs(msize, 'hexa', 'toroid');
98 %
99 % The neighbors can also be calculated for high-dimensional grids:
100 % Ne1 = som_unit_neighs([4 4 4 4 4 4]);
101 %
102 % SEE ALSO
103 %
104 % som_neighborhood Calculate N-neighborhoods of map units.
105 % som_unit_coords Calculate grid coordinates.
106 % som_unit_dists Calculate interunit distances.
107 % som_connection Connection matrix.
108
109 % Copyright (c) 1997-2000 by the SOM toolbox programming team.
110 % http://www.cis.hut.fi/projects/somtoolbox/
111
112 % Version 1.0beta juuso 141097
113 % Version 2.0beta juuso 101199
114
115 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
116 %% Check arguments
117
118 error(nargchk(1, 3, nargin));
119
120 % default values
121 sTopol = som_set('som_topol','lattice','rect');
122
123 % topol
124 if isstruct(topol),
125 switch topol.type,
126 case 'som_map', sTopol = topol.topol;
127 case 'som_topol', sTopol = topol;
128 end
129 elseif iscell(topol),
130 for i=1:length(topol),
131 if isnumeric(topol{i}), sTopol.msize = topol{i};
132 elseif ischar(topol{i}),
133 switch topol{i},
134 case {'rect','hexa'}, sTopol.lattice = topol{i};
135 case {'sheet','cyl','toroid'}, sTopol.shape = topol{i};
136 end
137 end
138 end
139 else
140 sTopol.msize = topol;
141 end
142 if prod(sTopol.msize)==0, error('Map size is 0.'); end
143
144 % lattice
145 if nargin>1 & ~isempty(lattice) & ~isnan(lattice), sTopol.lattice = lattice; end
146
147 % shape
148 if nargin>2 & ~isempty(shape) & ~isnan(shape), sTopol.shape = shape; end
149
150 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
151 %% Action
152
153 % distances between each map unit
154 Ud = som_unit_dists(sTopol);
155
156 % 1-neighborhood are those units the distance of which is equal to 1
157 munits = prod(sTopol.msize);
158 Ne1 = sparse(zeros(munits));
159 for i=1:munits,
160 inds = find(Ud(i,:)<1.01 & Ud(i,:)>0); % allow for rounding error
161 Ne1(i,inds) = 1;
162 end
163
164 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%