comparison toolboxes/FullBNT-1.0.7/KPMtools/subsets.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function [T, bitv] = subsets(S, U, L, sorted, N)
+% SUBSETS Create a set of all the subsets of S which have cardinality <= U and >= L
+% T = subsets(S, U, L)
+% U defaults to length(S), L defaults to 0.
+% So subsets(S) generates the powerset of S.
+%
+% Example:
+% T = subsets(1:4, 2, 1) 
+% T{:} = 1, 2, [1 2], 3, [1 3], [2 3], 4, [1 4], [2 4], [3 4]
+%
+% T = subsets(S, U, L, sorted)
+% If sorted=1, return the subsets in increasing size
+%
+% Example:
+% T = subsets(1:4, 2, 1, 1) 
+% T{:} = 1, 2, 3, 4, [1 2], [1 3], [2 3], [1 4], [2 4], [3 4]
+%
+% [T, bitv] = subsets(S, U, L, sorted, N)
+% Row i of bitv is a bit vector representation of T{i},
+% where bitv has N columns (representing 1:N).
+% N defaults to max(S).
+%
+% Example:
+% [T,bitv] = subsets(2:4, 2^3, 0, 0, 5)
+% T{:} = [], 2, 3, [2 3], 4, [2 4], [3 4], [2 3 4]
+% bitv=
+%     0     0     0     0     0
+%     0     1     0     0     0
+%     0     0     1     0     0
+%     0     1     1     0     0
+%     0     0     0     1     0
+%     0     1     0     1     0
+%     0     0     1     1     0
+%     0     1     1     1     0
+
+n = length(S);
+
+if nargin < 2, U = n; end
+if nargin < 3, L = 0; end
+if nargin < 4, sorted = 0; end
+if nargin < 5, N = max(S); end
+
+bits = ind2subv(2*ones(1,n), 1:2^n)-1;
+sm = sum(bits,2);
+masks = bits((sm <= U) & (sm >= L), :);
+m = size(masks, 1);
+T = cell(1, m);
+for i=1:m
+  s = S(find(masks(i,:)));
+  T{i} = s;
+end
+
+if sorted 
+  T = sortcell(T);
+end
+
+bitv = zeros(m, N);
+bitv(:, S) = masks;