OBTW, in this case A,B are floating point values and am actually using ismembertol because exact comparison fails for some elements...
ISMEMBER() modified result desired
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[lia,locb]=ismember(A,B);
returns the first/last matching location in B of the elements in A that occur in B depending on which optional parameters one chooses. That's fine for many cases, but...
If it is desired to do a 1:1 matching of elements in A to their corresponding mates in B, a modified behavior would be a desirable option if there are repeated elements -- locB could return the next match after the previous for those elements that may not be unique in either array.
This can be done in a loop, of course, by making a search for each element in A in turn, either keeping an indexing variable as to last location for each element previously located or, conversely, marking the location in B with a missing value or somesuch.
That's the problem, the question is --
Is there some function which already does this that I'm not aware of/can't find or a "more cleverer" way to make the match?
5 Kommentare
Jan
am 21 Jan. 2019
What about a small example?
A = [1, 2, 3, 1, 2, 3];
B = [2, 2, 2, 3, 3];
Is the wanted output this:
lia = [0, 1, 1, 0, 1, 1] % as logical
locb = [0, 1, 4, 0, 2, 5]
% ^ ^ would be 1 and 4 for standard ISMEMBER
Antworten (2)
Jan
am 21 Jan. 2019
Bearbeitet: Jan
am 21 Jan. 2019
Do you mean something like this:
function [lia, locb] = ismemberNext(A, B)
lia = false(size(A));
locb = zeros(size(A));
for iA = 1:numel(A)
match = (A(iA) == B);
if any(match)
lia(iA) = true;
index = find(match, 1);
locb(iA) = index;
B(index) = NaN; % Mask first match for following calls
end
end
end
2 Kommentare
Guillaume
am 21 Jan. 2019
Maybe I misunderstood the problem, but ismembertol already has the option to return all matching indices in B:
[found, where] = ismembertol(A, B, 'OutputAllIndices', true)
3 Kommentare
Guillaume
am 21 Jan. 2019
Are the A that match the same set of B exactly identical? If so, then it's easily solved. If there's a small tolerance on the As as well, then I'll have to think about it.
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