Simil to VLOOKUP (but ismember index 0)
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Hello, I have array A 10x1 and array B 3x2 as below
A=[1; 2; 3; 4; 5; 6; 7; 8; 9; 10];
B=[2 100; 4 500; 7 300];
I need to add to the A matrix the values according to the second column of B.
Output should be
A=[1 NaN; 2 100; 3 NaN; 4 500; 5 NaN; 6 NaN; 7 300; 8 NaN; 9 NaN; 10 NaN];
Cannot use ismember because I will have a 0 index (*)
Is there a way to solve this? Thanks
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Guillaume
2014-11-22
A simple way would be to fill the 2nd column of A with NaNs and replace some with logical addressing using ismember:
A=[1; 4; 3; 2; 5; 6; 7; 8; 9; 10]; %changed to make sure it works regardless of ordering
B=[2 100; 7 500; 4 300]; %changed to make sure it works regardless of ordering
A = [A nan(size(A, 1), 1)];
[row, locb] = ismember(A, B(:, 1));
A(row, 2) = B(locb(row), 2)
Another option is to use intersect instead of ismember and just use the indices it returns:
A=[1; 4; 3; 2; 5; 6; 7; 8; 9; 10]; %changed to make sure it works regardless of ordering
B=[2 100; 7 500; 4 300]; %changed to make sure it works regardless of ordering
A = [A nan(size(A, 1), 1)];
[~, ia, ib] = intersect(A, B(:, 1));
A(ia, 2) = B(ib, 2)
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