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- function f = calcposition(list,x)
- % function f = calcposition(list,x)
- %
- % <list> is a vector with unique elements (must be positive integers)
- % <x> is a vector whose elements are in <list>.
- % elements can be in any order and repeats are okay.
- %
- % return a vector the same length as <x> with indices relative to <list>.
- %
- % example:
- % isequal(calcposition([5 3 2 4],[2 2 5]),[3 3 1])
- % construct a vector that gives the correct index for X if you extract the Xth element
- xrank = NaN*zeros(1,max(list)); % if max(list) is big, this is ouch
- xrank(list) = 1:length(list);
- % get the answers
- f = xrank(x);
- % sanity check
- assert(~any(isnan(f)),'<list> does not subsume <x>');
- % NICER, BUT SLOWER:
- % % init
- % f = zeros(size(x));
- % % do it
- % xu = union(x,[]);
- % for p=1:length(xu)
- % temp = find(list==xu(p));
- % assert(~isempty(temp),'<list> does not subsume <x>');
- % f(x==xu(p)) = temp; % POTENTIALLY SLOW. see commented code below for a faster but less general solution
- % end
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