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Diffstat (limited to 'sourcecodes/bnt-master/KPMtools/subsets.m')
| -rw-r--r-- | sourcecodes/bnt-master/KPMtools/subsets.m | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/sourcecodes/bnt-master/KPMtools/subsets.m b/sourcecodes/bnt-master/KPMtools/subsets.m new file mode 100644 index 00000000..47f999f0 --- /dev/null +++ b/sourcecodes/bnt-master/KPMtools/subsets.m @@ -0,0 +1,58 @@ +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; |
