Let say I have 3 MATs
X = [ 1 3 9 10 ];
Y = [ 1 9 11 20];
Z = [ 1 3 9 11 ];
Now I would like to find the values that appear only once, and to what array they belong to
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The values that appear once in one of the vectors, or appear once counting the three vectors? In your example no value appears twice in a single vector, but they do if you count the three vectors.user2261062– user22610622016-10-10 07:39:59 +00:00Commented Oct 10, 2016 at 7:39
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2 Answers
I generalized EBH's answer to cover flexible number of arrays, arrays with different sizes and multidimensional arrays. This method also can only deal with integer-valued arrays:
function [uniq, id] = uniQ(varargin)
combo = [];
idx = [];
for ii = 1:nargin
combo = [combo; varargin{ii}(:)]; % merge the arrays
idx = [idx; ii*ones(numel(varargin{ii}), 1)];
end
counts = histcounts(combo, min(combo):max(combo)+1);
ids = find(counts == 1); % finding index of unique elements in combo
uniq = min(combo) - 1 + ids(:); % constructing array of unique elements in 'counts'
id = zeros(size(uniq));
for ii = 1:numel(uniq)
ids = find(combo == uniq(ii), 1); % finding index of unique elements in 'combo'
id(ii) = idx(ids); % assigning the corresponding index
end
And this is how it works:
[uniq, id] = uniQ([9, 4], 15, randi(12,3,3), magic(3))
uniq =
1
7
11
12
15
id =
4
4
3
3
2
1 Comment
EBH
Nice! I didn't have time to continue generelizing it.
If you are only dealing with integers and your vectors are equally sized (all with the same number of elements), you can use histcounts for a quick search for unique elements:
X = [1 -3 9 10];
Y = [1 9 11 20];
Z = [1 3 9 11];
XYZ = [X(:) Y(:) Z(:)]; % one matrix with all vectors as columns
counts = histcounts(XYZ,min(XYZ(:)):max(XYZ(:))+1);
R = min(XYZ(:)):max(XYZ(:)); % range of the data
unkelem = R(counts==1);
and then locate them using a loop with find:
pos = zeros(size(unkelem));
counter = 1;
for k = unkelem
[~,pos(counter)] = find(XYZ==k);
counter = counter+1;
end
result = [unkelem;pos]
and you get:
result =
-3 3 10 20
1 3 1 2
so -3 3 10 20 are unique, and they appear at the 1 3 1 2 vectors, respectively.
