Mercurial > hg > camir-aes2014

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

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
first hg version after svn
author wolffd
date Tue, 10 Feb 2015 15:05:51 +0000
parents
children
comparison
equal deleted inserted replaced
-1:000000000000 0:e9a9cd732c1e
1 function Ne = som_neighborhood(Ne1,n)
2
3 %SOM_NEIGHBORHOOD Calculate neighborhood matrix.
4 %
5 % Ne = som_neighborhood(Ne1,n)
6 %
7 % Ne = som_neighborhood(Ne1);
8 % Ne = som_neighborhood(som_unit_neighs(topol),2);
9 %
10 % Input and output arguments ([]'s are optional):
11 % Ne1 (matrix, size [munits m]) a sparse matrix indicating
12 % the units in 1-neighborhood for each map unit
13 % [n] (scalar) maximum neighborhood which is calculated, default=Inf
14 %
15 % Ne (matrix, size [munits munits]) neighborhood matrix,
16 % each row (and column) contains neighborhood
17 % values from the specific map unit to all other
18 % map units, or Inf if the value is unknown.
19 %
20 % For more help, try 'type som_neighborhood' or check out online documentation.
21 % See also SOM_UNIT_NEIGHS, SOM_UNIT_DISTS, SOM_UNIT_COORDS, SOM_CONNECTION.
22
23 %%%%%%%%%%%%% DETAILED DESCRIPTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
24 %
25 % som_neighborhood
26 %
27 % PURPOSE
28 %
29 % Calculate to which neighborhood each map unit belongs to relative to
30 % each other map unit, given the units in 1-neighborhood of each unit.
31 %
32 % SYNTAX
33 %
34 % Ne = som_neighborhood(Ne1);
35 % Ne = som_neighborhood(Ne1,n);
36 %
37 % DESCRIPTION
38 %
39 % For each map unit, finds the minimum neighborhood to which it belongs
40 % to relative to each other map unit. Or, equivalently, for each map
41 % unit, finds which units form its k-neighborhood, where k goes from
42 % 0 to n.
43 %
44 % The neighborhood is calculated iteratively using the reflexivity of
45 % neighborhood.
46 % let N1i be the 1-neighborhood set a unit i
47 % and let N11i be the set of units in the 1-neighborhood of any unit j in N1i
48 % then N2i (the 2-neighborhood set of unit i) is N11i \ N1i
49 %
50 % Consider, for example, the case of a 5x5 map. The neighborhood in case of
51 % 'rect' and 'hexa' lattices (and 'sheet' shape) for the unit at the
52 % center of the map are depicted below:
53 %
54 % 'rect' lattice 'hexa' lattice
55 % -------------- --------------
56 % 4 3 2 3 4 3 2 2 2 3
57 % 3 2 1 2 3 2 1 1 2 3
58 % 2 1 0 1 2 2 1 0 1 2
59 % 3 2 1 2 3 2 1 1 2 3
60 % 4 3 2 3 4 3 2 2 2 3
61 %
62 % Because the iterative procedure is rather slow, the neighborhoods
63 % are calculated upto given maximal value. The uncalculated values
64 % in the returned matrix are Inf:s.
65 %
66 % REQUIRED INPUT ARGUMENTS
67 %
68 % Ne1 (matrix) Each row contains 1, if the corresponding unit is adjacent
69 % for that map unit, 0 otherwise. This can be calculated
70 % using SOM_UNIT_NEIGHS. The matrix can be sparse.
71 % Size munits x munits.
72 %
73 % OPTIONAL INPUT ARGUMENTS
74 %
75 % n (scalar) Maximal neighborhood value which is calculated,
76 % Inf by default (all neighborhoods).
77 %
78 % OUTPUT ARGUMENTS
79 %
80 % Ne (matrix) neighborhood values for each map unit, size is
81 % [munits, munits]. The matrix contains the minimum
82 % neighborhood of unit i, to which unit j belongs,
83 % or Inf, if the neighborhood was bigger than n.
84 %
85 % EXAMPLES
86 %
87 % Ne = som_neighborhood(Ne1,1); % upto 1-neighborhood
88 % Ne = som_neighborhood(Ne1,Inf); % all neighborhoods
89 % Ne = som_neighborhood(som_unit_neighs(topol),4);
90 %
91 % SEE ALSO
92 %
93 % som_unit_neighs Calculate units in 1-neighborhood for each map unit.
94 % som_unit_coords Calculate grid coordinates.
95 % som_unit_dists Calculate interunit distances.
96 % som_connection Connection matrix.
97
98 % Copyright (c) 1999-2000 by the SOM toolbox programming team.
99 % http://www.cis.hut.fi/projects/somtoolbox/
100
101 % Version 1.0beta juuso 141097
102 % Version 2.0beta juuso 101199
103
104 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
105 %% Check arguments
106
107 error(nargchk(1, 2, nargin));
108
109 if nargin<2, n=Inf; end
110
111 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
112 %% Action
113
114 % initialize
115 if issparse(Ne1), Ne = full(Ne1); else Ne = Ne1; end
116 clear Ne1
117 [munits dummy] = size(Ne);
118 Ne(find(Ne==0)) = NaN;
119 for i=1:munits, Ne(i,i)=0; end
120
121 % Calculate neighborhood distance for each unit using reflexsivity
122 % of neighborhood:
123 % let N1i be the 1-neighborhood set a unit i
124 % then N2i is the union of all map units, belonging to the
125 % 1-neighborhood of any unit j in N1i, not already in N1i
126 k=1;
127 if n>1,
128 fprintf(1,'Calculating neighborhood: 1 ');
129 N1 = Ne;
130 N1(find(N1~=1)) = 0;
131 end
132 while k<n & any(isnan(Ne(:))),
133 k=k+1;
134 fprintf(1,'%d ',k);
135 for i=1:munits,
136 candidates = isnan(Ne(i,:)); % units not in any neighborhood yet
137 if any(candidates),
138 prevneigh = find(Ne(i,:)==k-1); % neighborhood (k-1)
139 N1_of_prevneigh = any(N1(prevneigh,:)); % union of their N1:s
140 Nn = find(N1_of_prevneigh & candidates);
141 if length(Nn), Ne(i,Nn) = k; Ne(Nn,i) = k; end
142 end
143 end
144 end
145 if n>1, fprintf(1,'\n'); end
146
147 % finally replace all uncalculated distance values with Inf
148 Ne(find(isnan(Ne))) = Inf;
149
150 return;
151
152 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
153 %% faster version?
154
155 l = size(Ne1,1); Ne1([0:l-1]*(l+1)+1) = 1; Ne = full(Ne1); M0 = Ne1; k = 2;
156 while any(Ne(:)==0), M1=(M0*Ne1>0); Ne(find(M1-M0))=k; M0=M1; k=k+1; end
157 Ne([0:l-1]*(l+1)+1) = 0;